Search
Member View
/ Center for Advanced Computation
Theoretical High Energy Physics
Prof. Pyungwon Ko works on particle physics phenomenology. The main research areas are flavor physics and CP violation within and beyond the standard model, applications of QCD and its various effective field theories, dynamical symmetry breaking and dark matter physics.



Publication at kias
NUMBER  
AUTHOR  Ko, Pyungwon 
TITLE  Proceedings of the second MADANALYSIS 5 workshop on LHC recasting in Korea 
ARCHIVE  
FILE  
JOURNAL  MODERN PHYSICS LETTERS A, 2021 
ABSTRACT  We document the activities performed during the second MADANALYSIS 5 workshop on LHC recasting, that was organised in KIAS (Seoul, Korea) on February 1220, 2020. We detail the implementation of 12 new ATLAS and CMS searches in the MADANALYSIS 5 Public Analysis Database, and the associated validation procedures. Those searches probe the production of extra gauge and scalar/pseudoscalar bosons, supersymmetry, seesaw models and deviations from the Standard Model in fourtop production. 

Publication at kias
NUMBER  
AUTHOR  Ko, P.,Kim, Jongkuk 
TITLE  XENON1T excess in local Z(2) DM models with light dark sector 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B, 2020 
ABSTRACT  Recently XENON1T Collaboration announced that they observed some excess in the electron recoil energy around a 23 keV. We show that this excess can be interpreted as exothermic scattering of excited dark matter on atomic electron through dark photon exchange. We consider DM models with local dark U(1) gauge symmetry that is spontaneously broken into its Z(2) subgroup by KraussWilczek mechanism. In order to explain the XENON1T excess with the correct DM thermal relic density within freezeout scenario, all the particles in the dark sector should be light enough, namely similar to O (100) MeV for scalar DM and similar to O (1  10) MeV for fermion DM cases. And even lighter dark Higgs phi plays an important role in the DM relic density calculation: XX dagger > Zphi for scalar DM (X) and chi(chi) over bar > phi phi for fermion DM (chi) assuming m(Z) > m(chi). Both of them are in the pwave annihilation, and one can easily evade stringent bounds from Planck data on CMB on the swave annihilations, assuming other dangerous swave annihilations are kinematically forbidden. (C) 2020 The Author(s). Published by Elsevier B.V. 

Publication at kias
NUMBER  
AUTHOR  Ko, Pyungwon,Matsui, Toshinori,Tang, YiLei 
TITLE  Dark matter bound state formation in fermionic Z(2) DM model with light dark photon and dark Higgs boson 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2020 
ABSTRACT  If fermionic dark matter (DM) is stabilized by dark U(1) gauge symmetry that is spontaneously broken into its subgroup Z(2), the particle contents of the model becomes very rich: DM and excited DM, both of them are Majorana fermions, as well as two dark force mediators, dark photon and dark Higgs boson are naturally present due to the underlying dark gauge symmetry. In this paper, we study the DM bound state formation processes within this scenario, assuming both dark photon and dark Higgs are light mediators and including the effects of excited DM. The Goldstone boson contributions to the potential matrix in the Schrodinger equations are found to be important. The emissions of a longitudinal vector boson (or somehow equivalently a Goldstone boson) during the DM bound state formations are crucial to induce a significant reannihilation process, reducing the dark matter relic abundance. Most of the stringent constraints for this kind of dark matter considered in the literature are simply evaded. 

Publication at kias
NUMBER  P20055 
AUTHOR  Ko, Pyungwon,Kang, Dong Woo 
TITLE  Heavy dark matter through the dilaton portal 
ARCHIVE  2007.08546 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2020 
ABSTRACT  We reexamine current and future constraints on a heavy dilaton coupled to a simple dark sector consisting of a Majorana fermion or a Stuckelberg vector field. We include three different treatments of dilatonHiggs mixing, paying particular attention to a gaugeinvariant formulation of the model. Moreover, we also invite readers to reexamine effective field theories of vector dark matter, which we show are missing important terms. Along with the latest Higgs coupling data, heavy scalar search results, and dark matter density/direct detection constraints, we study the LHC bounds on the model and estimate the prospects of dark matter production at the future HLLHC and 100 TeV FCC colliders. We additionally compute novel perturbative unitarity constraints involving vector dark matter, dilaton and gluon scattering. 

Publication at kias
NUMBER  
AUTHOR  Ko, Pyungwon 
TITLE  Reinterpretation of LHC results for new physics: status and recommendations after run 2 
ARCHIVE  
FILE  
JOURNAL  SCIPOST PHYSICS, 2020 
ABSTRACT  We report on the status of efforts to improve the reinterpretation of searches and measurements at the LHC in terms of models for new physics, in the context of the LHC Reinterpretation Forum. We detail current experimental offerings in direct searches for new particles, measurements, technical implementations and Open Data, and provide a set of recommendations for further improving the presentation of LHC results in order to better enable reinterpretation in the future. We also provide a brief description of existing software reinterpretation frameworks and recent global analyses of new physics that make use of the current data. 

Publication at kias
NUMBER  
AUTHOR  Ko, P. 
TITLE  Top FCNC induced by a Z boson 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D, 2020 
ABSTRACT  We consider a Z model in which the Z boson couples only to up and top quarks. For a simple setup, one can consider a familydependent U(1) symmetry, under which only righthanded uptype quarks are charged. After symmetry breaking, the righthanded quarks mix with each other, and top flavorchanging neutral currents (FCNCs) mediated by the Z boson can be generated at tree level. We take into account several processes at the parton level to probe the top FCNCs and find that the samesign top quark pair production or the triple top quark production is the most capable of testing the top FCNCs. We also consider a few nonFCNC processes to probe the Z boson, for example, dijet production at the LHC. Finally, we perform numerical analysis at detector level and find that the samesign top quark pair production provides a much more stringent bound on the FCNC coupling than the other processes in most of the parameter space. 

Publication at kias
NUMBER  P19034 
AUTHOR  Ko, Pyungwon,Park, Jiwon,Li, Jinmian 
TITLE  Correlation between RD() and top quark FCNC decays in leptoquark models 
ARCHIVE  arXiv:1812.08484 title=ARCHIVE target=_blank > hepph > arXiv:1812.08484 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2019 
ABSTRACT  Some interpretations of RD anomaly in B meson decay using leptoquark (LQ) models can also generate top quark decays through Flavor Changing Neutral Current (FCNC). In this work we focus on two LQs, i.e. scalar S1 and vector U1 which are both singlet under the SU(2)(L) gauge group in the Standard Model (SM). We investigate their implications on the 3body top FCNC decays t > cl(i)l(j) at tree level and the 2body t > cV at oneloop level, with l being the SM leptons and V = gamma, Z, g being the SM gauge bosons. We utilize the 2 sigma parameter fitting ranges of the LQ models and find that Br(t > cl(i)l(j)) at tree level can reach O(10(6)) and Br(t > cV) at oneloop level can reach O(10(10)). Some quick collider search prospects are also analyzed. 

Publication at kias
NUMBER  P19009 
AUTHOR  Ko, P.,Nomura, Takaaki 
TITLE  b > s mu(+)mu() anomalies and related phenomenology in U(1)(B3x mu)Lmux(tau)L(tau) flavor gauge models 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2019 
ABSTRACT  We propose a generation dependent lepton/baryon gauge symmetry, UX (with x + x = 1 for anomaly cancellation), as a possible solution for the b s(+) anomalies. By introducing two Higgs doublet fields, we can reproduce the observed CKM matrix, and generate flavor changing Z interactions in the quark sector. Thus one can explain observed anomalies in b s(+) decay with the lepton nonuniversal U(1)(X) charge assignments. We show the minimal setup explaining bs(+) anomalies, neutrino masses and mixings and dark matter candidate, taking into account experimental constraints of flavor physics such as charged lepton flavor violations and the BsB 

Publication at kias
NUMBER  P18105 
AUTHOR  Ko, Pyungwon,Yokoya, Hiroshi,Chen, Junmou 
TITLE  Light dark matter showering under broken dark U(1) revisited 
ARCHIVE  hepph/1807.00530 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2019 
ABSTRACT  It was proposed recently that different chiralities of the dark matter (DM) fermion under a broken dark U(1) gauge group can lead to distinguishable signatures at the LHC through shower patterns, which may reveal the mass origin of the dark sector. We study this subject further by examining the dark shower of two simplified models, the dubbed Chiral Model and the Vector Model. We derive a more complete set of collinear splitting functions with power corrections, specifying the helicities of the initial DM fermion and including the contribution from an extra degree of freedom, the dark Higgs boson. The dark shower is then implemented with these splitting functions, and the new features resulting from its correct modelling are emphasized. It is shown that the DM fermion chirality can be differentiated by measuring dark shower patterns, especially the DM jet energy profile, which is almost independent of the DM energy. 

Publication at kias
NUMBER  
AUTHOR  Ko, P.,Li, Jinmian 
TITLE  Impact of the 125 GeV Higgs boson on singlet fermion dark matter searches at the LHC 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D, 2018 
ABSTRACT  The search for singlet fermion dark matter at highenergy colliders is commonly analyzed with a singlet scalar mediator, which however violates the standard model (SM) gauge invariance, renormalizability and unitarity. These problems can be cured by introducing a mixing between the singlet scalar s and the SM Higgs boson h. Thus one has to consider two scalar mediators h(1) and h(2), where h(1) is identified as the discovered 125 GeV Higgs boson. As a specific example, we consider the dark matter (DM) search in the t (t) over bar + is not an element of(T) channel. According to the masses of dark matter and two scalar mediators, we classify the process into four cases. By investigating the total cross sections and differential distributions, we find that the contribution of the 125 GeV Higgs boson h(1) cannot be neglected in all cases and can even dominate once h(1) is on shell in dark matter production. Further, we study the impact of h(1) on the LHC bounds of dark matter searches in the hadronic and semileptonic channels with the integrated luminosity of 36 fb(1). Finally we make a brief comment that h(1) should be also considered in the vector DM search at highenergy colliders. 

Publication at kias
NUMBER  
AUTHOR  Ko, Pyungwon 
TITLE  Particle, Astroparticle Physics and Cosmology in Dark Matter Models with Dark Gauge Symmetries 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF THE KOREAN PHYSICAL SOCIETY, 2018 
ABSTRACT  In this review, I describe a class of dark matter (DM) models where DM is either stable due to unbroken dark gauge symmetries, or longlived due to accidental global symmetries resulting from the underlying dark gauge symmetries. Within these models, I discuss various topics on DM in the context of particle and astroparticle physics and cosmology: DM thermal relic density and (in)direct detection, Higgs inflation assisted with Higgs portal interaction, dark radiation (DR), DMDR interaction and suppression of the matter power spectrum at large k, strong first order phase transition and gravitational wave production, etc.. Especially I emphasize the importance of dark gauge symmetries, unitarity and renormalizability, and the limitation of the DM effective field theory (EFT) or simplified models for DM searches at high energy colliders, including the role of dark Higgs boson and dark gauge bosons. 

Publication at kias
NUMBER  
AUTHOR  Ko, Pyungwon,Natale, Alexander 
TITLE  Resolving phenomenological problems with stronglyinteractingmassiveparticle models with dark vector resonances 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D, 2018 
ABSTRACT  We consider a light dark matter candidate that is produced by the freezeout mechanism with 3 > 2 annihilations, the socalled strongly interacting massive particles (SIMPs). SIMPs are identified as dark pions in dark chiral perturbation theory (ChPT) in which both light mass and strong coupling needed for SIMPs can be realized by strong dynamics. In QCDlike theories with SU(3)(L) x SU(3)(R)/SU(3)(V) flavor symmetry, including dark vector mesons in the hidden local symmetry scheme, we illustrate that dark vector mesons unitarize the dark ChPT efficiently, thus determining the correct relic density condition within the validity of the dark ChPT. 

Publication at kias
NUMBER  
AUTHOR  Ko, P.,Li, Jinmian 
TITLE  Prospects for discovery and spin discrimination of dark matter in Higgs portal DM models and their extensions at 100 TeV pp collider 
ARCHIVE  
FILE  
JOURNAL  EUROPEAN PHYSICAL JOURNAL C, 2018 
ABSTRACT  We study the discovery and discriminating prospects of the Higgs portal dark matter (DM) models for scalar, fermion and vector DM and their extensions in protonproton (pp) collisions. The t (t) over bar +DM associated production in dileptonic final states is considered, in which the stransverse mass of two leptons is found to be effective in suppressing the Standard Model backgrounds along with the missing transverse energy and the angle between two leptons. The distributions of missing transverse energy and polar angle between two leptons are used for a discrimination of the spin nature of DM. For the proposed benchmark points, the discovery/exclusion can be made with an integrated luminosity less than 1 ab(1) given a 1% systematic uncertainty, while the spin discrimination require integrated luminosity of a few O(10) ab(1) given a 0.5% systematic uncertainty. The DM phenomenology is also discussed. A consistent DM candidate can be obtained either by extending our model where the Higgs portal couples to excited dark states that decay into DM, or modifying the coupling form into pseudoscalar. 

Publication at kias
NUMBER  
AUTHOR  Ko, Pyungwon,Baek, Seungwon,Wu, Peiwen 
TITLE  Heavy quarkphilic scalar dark matter with a vectorlike fermion portal 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, 2018 
ABSTRACT  The absence of confirmed signal in dark matter (DM) direct detection (DD) may suggest weak interaction strengths between DM and the abundant constituents inside nucleon, i.e. gluons and valence light quarks. In this work we consider a real scalar dark matter S interacting only with SU(2)(L) singlet Uptype quarks Ui, = uR, c(R), t(R) via a vector like fermion 0 which has the same quantum number as Ui. The DMnucleon scattering can proceed through both hmediated Higgs portal (HP) and psimediated vectorlike portal (VLP), in which HP can receive sizable radiative corrections through the new fermions. We first study the separate constraints on the new Yukawa couplings y(i) and find that the constraints of XENON1T results are strong on y(1) from VLP scattering and on y(3) from its radiative contributions to HP scattering. Since both DMlight quark interactions and HP have been well studied in the existing literature, we move forward to focus on DM heavy quark interactions. Since there is no valence c, t quark inside nucleons at mu(had) similar to 1 GeV, y(2), y(3) interactions are manifested in DMgluon scattering at loop level. We find that renormalization group equation (RGE) and heavy quark threshold effects are important if one calculates the DMnucleon scattering rate apsi at Mad 1 GeV while constructing the effective theory at mu(LEFT) similar to m(Z). For the benchmarks y(3) = 0.5, y(2) = 0.5,1, 3, combined results from Omega(DM)h(2) similar or equal to 0.12, XENON1T, FermiLAT, 13 TeV LHC data have almost excluded m(s) < m(t)/2 when only DM{c, t} interactions are considered. FCNC of top quark can be generated at both tree level t > psi(*),S > cSS and loop level t > c + gamma/g/Z, of which the branching fractions are typically below 10(9) after passing the other constraints, which are still safe from the current top quark width measurements. 

Publication at kias
NUMBER  P18013 
AUTHOR  Ko, Pyungwon,Matsui, Toshinori 
TITLE  Gravitational waves from first order electroweak phase transition in models with the U(1)(X) gauge symmetry 
ARCHIVE  arXiv:1802.02947 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2018 
ABSTRACT  We consider a standard model extension equipped with a dark sector where the U(1)(X) Abelian gauge symmetry is spontaneously broken by the dark Higgs mechanism. In this framework, we investigate patterns of the electroweak phase transition as well as those of the dark phase transition, and examine detectability of gravitational waves (GWs) generated by such strongly first order phase transition. It is pointed out that the collider bounds on the properties of the discovered Higgs boson exclude a part of parameter space that could otherwise generate detectable GWs. After imposing various constraints on this model, it is shown that GWs produced by multistep phase transitions are detectable at future spacebased interferometers, such as LISA and DECIGO, if the dark photon is heavier than 25 GeV. Furthermore, we discuss the complementarity of dark photon searches or dark matter searches with the GW observations in these models with the dark gauge symmetry. 

Publication at kias
NUMBER  P17047 
AUTHOR  Ko, P.,Matsui, Toshinori,Kang, Zhaofeng 
TITLE  Strong first order EWPT & strong gravitational waves in Z(3)symmetric singlet scalar extension 
ARCHIVE  arXiv:1706.09721 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2018 
ABSTRACT  The nature of electroweak (EW) phase transition (PT) is of great importance. It may give a clue to the origin of baryon asymmetry if EWPT is strong first order. Although it is a cross over within the standard model (SM), a great many extensions of the SM are capable of altering the nature. Thus, gravitational wave (GW), which is supposed to be relics of strong first order PT, is a good complementary probe to new physics beyond SM (BSM). We in this paper elaborate the patterns of strong first order EWPT in the next to simplest extension to the SM Higgs sector, by introducing a Z(3)symmetric singlet scalar. We find that, in the Z(3)symmetric limit, the tree level barrier could lead to strong first order EWPT either via three or twostep PT. Moreover, they could produce two sources of GW, despite of the undetectability from the firststep strong first order PT for the near future GW experiments. But the other source with significant supercooling which then gives rise to alpha similar to O(0.1) almost can be wholly covered by future spacebased GW interferometers such as eLISA, DECIGO and BBO. 

Publication at kias
NUMBER  P17043 
AUTHOR  Ko, P. 
TITLE  Hidden charged dark matter and chiral dark radiation 
ARCHIVE  arXiv:1706.05605 
FILE  
JOURNAL  PHYSICS LETTERS B, 2017 
ABSTRACT  In the light of recent possible tensions in the Hubble constant H0 and the structure growth rate sigma(8) between the Planck and other measurements, we investigate a hiddencharged dark matter (DM) model where DM interacts with hidden chiral fermions, which are charged under the hidden SU(N) and U(1) gauge interactions. The symmetries in this model assure these fermions to be massless. The DM in this model, which is a Dirac fermion and singlet under the hidden SU(N), is also assumed to be charged under the U(1) gauge symmetry, through which it can interact with the chiral fermions. Below the confinement scale of SU(N), the hidden quark condensate spontaneously breaks the U(1) gauge symmetry such that there remains a discrete symmetry, which accounts for the stability of DM. This condensate also breaks a flavor symmetry in this model and NambuGoldstone bosons associated with this flavor symmetry appear below the confinement scale. The hidden U(1) gauge boson and hidden quarks/NambuGoldstone bosons are components of dark radiation (DR) above/below the confinement scale. These light fields increase the effective number of neutrinos by delta Neff similar or equal to 0.59 above the confinement scale for N = 2, resolving the tension in the measurements of the Hubble constant by Planck and Hubble Space Telescope if the confinement scale is less than or similar to 1 eV. DM and DR continuously scatter with each other via the hidden U(1) gauge interaction, which suppresses the matter power spectrum and results in a smaller structure growth rate. The DM sector couples to the Standard Model sector through the exchange of a real singlet scalar mixing with the Higgs boson, which makes it possible to probe our model in DM direct detection experiments. Variants of this model are also discussed, which may offer alternative ways to investigate this scenario. (C) 2017 The Author(s). Published by Elsevier B.V. 

Publication at kias
NUMBER  P17033 
AUTHOR  Ko, P.,Li, Jinmian 
TITLE  Characterizing Higgs portal dark matter models at the ILC 
ARCHIVE  arXiv:1705.02149 
FILE  
JOURNAL  EUROPEAN PHYSICAL JOURNAL C, 2017 
ABSTRACT  We study the dark matter (DM) discovery prospect and its spin discrimination in the theoretical framework of gauge invariant and renormalizable Higgs portal DM models at the ILC with root s = 500 GeV. In such models, the DM pair is produced in association with a Z boson. In the case of the singlet scalar DM, the mediator is just the SM Higgs boson, whereas for the fermion or vector DM there is an additional singlet scalar mediator that mixes with the SM Higgs boson, which produces significant observable differences. After careful investigation of the signal and backgrounds both at parton level and at detector level, we find the signal with hadronically decaying Z boson provides a better search sensitivity than the signal with leptonically decaying Z boson. Taking the fermion DM model as a benchmark scenario, when the DMmediator coupling g(chi) is relatively small, the DM signals are discoverable only for benchmark points with relatively light scalar mediator H2. The spin discriminating from scalar DM is always promising, while it is difficult to discriminate from vector DM. As for g(chi) approaching the perturbative limit, benchmark points with the mediator H2 in the full mass region of interest are discoverable. The spin discriminating aspects from both the scalar and the fermion DM are quite promising. 

Publication at kias
NUMBER  P17007 
AUTHOR  Ko, P.,Nomura, Takaaki 
TITLE  A flavor dependent gauge symmetry, predictive radiative seesaw and LHCb anomalies 
ARCHIVE  arXiv:1701.05788 
FILE  
JOURNAL  PHYSICS LETTERS B, 2017 
ABSTRACT  We propose a predictive radiative seesaw model at oneloop level with a flavor dependent gauge symmetry U(1)(xB3xemu+iota) tand Majorana fermion dark matter. For the neutrino mass matrix, we obtain an A(1) type texture ( with two zeros) that provides us several predictions such as the normal ordering for the neutrino masses. We analyze the constraints from lepton flavor violations, relic density of dark matter, and collider physics for the new U(1)(xB3) (xemu+iota) tgauge boson. Within the allowed region, the LHCb anomalies in B > K* mu (+) mu and B > Kl (+) l with l = e or mu can be resolved, and such Z could be also observed at the LHC. (C) 2017 The Authors. Published by Elsevier B.V. 

Publication at kias
NUMBER  P17015 
AUTHOR  Ko, P. 
TITLE  LHCb anomaly and B physics in flavored Z models with flavored Higgs doublets 
ARCHIVE  arXiv:1702.08666 
FILE  
JOURNAL  PHYSICAL REVIEW D, 2017 
ABSTRACT  We study an extended Standard Model with a gauged U(1) flavor symmetry, motivated not only by the fermion mass hierarchy but also by the excesses in B > K(*())ll reported by the LHCb collaborations. The U(1) charges are assigned to quarks and leptons in a flavordependent manner, and flavored Higgs doublets are also introduced in order to detail the Yukawa couplings at the renormalizable level. Then, the fermion mass hierarchy is realized by the vacuum alignment of the Higgs doublets. In this model, flavorchanging currents involving the gauge boson of U(1) and the scalars generated by the Higgs doublets are predicted and the observables in the B > K(*())ll process possibly deviate from the Standard Model predictions. We study the possibility that these new flavorchanging interactions can explain the excesses in the B > K(*())ll process, and we derive some predictions for the other flavorviolating processes based on the analysis. We specifically investigate the Delta F = 2 processes and the other B decays: e.g., B > Xs gamma and B > D(*())tau nu, where the deviations are reported by the Belle and BABAR collaborations. 

Publication at kias
NUMBER  
AUTHOR  Ko, P. 
TITLE  Probing a new strongly interacting sector via composite diboson resonances 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D, 2017 
ABSTRACT  Diphoton resonance was a crucial discovery mode for the 125 GeV Standard Model Higgs boson at the Large Hadron Collider (LHC). This mode or the more general diboson modes may also play an important role in probing for new physics beyond the Standard Model. In this paper, we consider the possibility that a diphoton resonance is due to a composite scalar or pseudoscalar boson, whose constituents are either new hyperquarks Q or scalar hyperquarks (Q) over tilde confined by a new hypercolor force at a confinement scale Lambda(h). Assuming the mass m(Q) (or m((Q) over tilde))>> Lambda(h), a diphoton resonance could be interpreted as either a Q (Q) over bar (S1(0)) state eta(Q) with J(PC) = 0(+) or a (Q) over tilde(Q) over tilde (+) (S1(0)) state eta((Q) over tilde) with J(PC) = 0(++) For the Q (Q) over bar scenario, there will be a spintriplet partner psi(Q) which is slightly heavier than eta(Q) due to the hyperfine interactions mediated by hypercolor gluon exchange; while for the (Q) over bar(Q) over bar (+) scenario, the spintriplet partner chi(Q) over tilde arises from higher radial excitation with nonzero orbital angular momentum. We consider productions and decays of eta(Q),eta(Q) over tilde,psi(Q),and psi((Q) over tilde) at the LHC using the nonrelativistic QCD factorization approach. We discuss how to test these scenarios by using the DrellYan process and the forward dijet azimuthal angular distributions to determine the JPC quantum number of the diphoton resonance. Constraints on the parameter space can be obtained by interpreting some of the small diphoton excesses reported by the LHC as the composite scalar or pseudoscalar of the model. Another important test of the model is the presence of a nearby hypercolorsinglet but coloroctet state like the S1(0) state eta(8)(Q) or eta(8)((Q) over tilde), which can also be constrained by dijet or monojet plus monophoton data. Both possibilities of a large or small width of the resonance can be accommodated, depending on whether the hyperglueball states are kinematically allowed in the final state or not. 

Publication at kias
NUMBER  P17010 
AUTHOR  Ko, P.,Nomura, Takaaki 
TITLE  Explaining B > K(*())l(+)l() anomaly by radiatively induced coupling in U(1)(mutau) gauge symmetry 
ARCHIVE  arXiv:1702.02699 
FILE  
JOURNAL  PHYSICAL REVIEW D, 2017 
ABSTRACT  We propose a scenario to generate flavor violating Z interactions at oneloop level by introducing U(1)(mutau) gauge symmetry, extra vectorlike quark doublets Q(a), and a singlet scalar chi. Both Q(a) and chi are charged under U(1)(mutau) and carry odd dark Z(2) parity. Assuming that chi is the dark matter (DM) of the Universe and imposing various constraints from a dark matter search, flavor physics, and a collider search for Q(a), one can show that radiative corrections to b > sZ*> sl(+)l() involving Q(a) and chi can induce Delta C9 similar to 1, which can resolve the LHCb anomalies related with B > K(*)l(+)l(). Therefore, both DM and B physics anomalies can be accommodated in the model. 

Publication at kias
NUMBER  P16074 
AUTHOR  Ko, P.,Tang, Yong 
TITLE  Residual nonAbelian dark matter and dark radiation 
ARCHIVE  arXiv:1609.02307 
FILE  
JOURNAL  PHYSICS LETTERS B, 2017 
ABSTRACT  We propose a novel particle physics model in which vector dark matter (VDM) and dark radiation (DR) originate from the same nonAbelian dark sector. We show an illustrating example where dark SU(3) is spontaneously broken into SU(2) subgroup by the nonzero vacuum expectation value (VEV) of a complex scalar in fundamental representation of SU(3). The massless gauge bosons associated with the residual unbroken SU(2) constitute DR and help to relieve the tension in Hubble constant measurements between Planck and Hubble Space Telescope. In the meantime, massive dark gauge bosons associated with the broken generators are VDM candidates. Intrinsically, this nonAbelian VDM can interact with nonAbelian DR in the cosmic background, which results in a suppressed matter power spectrum and leads to a smaller sigma(8) for structure formation. (C) 2017 The Author(s). Published by Elsevier B.V. 

Publication at kias
NUMBER  P17004 
AUTHOR  Ko, P.,Baek, Seungwon,Li, Jinmian 
TITLE  Minimal renormalizable simplified dark matter model with a pseudoscalar mediator 
ARCHIVE  1701.04131 
FILE  
JOURNAL  PHYSICAL REVIEW D, 2017 
ABSTRACT  We consider a minimal renormalizable and gauge invariant dark matter (DM) model, in which the singlet fermion DM has only axial couplings to a new pseudoscalar mediator. The mixing between the pseudoscalar mediator and the standard model (SM) Higgs boson induces the interactions between the DM and SM particles. The DM candidate in this model can provide the correct thermal relic density and evades all direct detections, while it can produce observable signals in indirect detection experiments due to its large annihilation cross section. A comparative study for DM phenomenology at the LHC is conducted for models with scalar mediators that have either scalar or pseudoscalar couplings to SM particles and the DM. We find that the three scenarios have distinguishable features in scalar decay branching ratio, DM pair production cross section as well as the signal reaches at the LHC. The LHC searches for some visible signals related to the scalar sector are also discussed. 

Publication at kias
NUMBER  P16065 
AUTHOR  Ko, Pyungwon,Matsui, Toshinori 
TITLE  Gravitational waves and Higgs boson couplings for exploring first order phase transition in the model with a singlet scalar field 
ARCHIVE  arXiv:1609.00297 
FILE  
JOURNAL  PHYSICS LETTERS B, 2017 
ABSTRACT  We calculate the spectrum of gravitational waves originated from strongly first order electroweak phase transition in the extended Higgs model with a real singlet scalar field. In order to calculate the bubble nucleation rate, we perform a twofield analysis and evaluate bounce solutions connecting the true and the false vacua using the oneloop effective potential at finite temperatures. Imposing the Sakharov condition of the departure from thermal equilibrium for baryogenesis, we survey allowed regions of parameters of the model. We then investigate the gravitational waves produced at electroweak bubble collisions in the early Universe, such as the sound wave, the bubble wall collision and the plasma turbulence. We find that the strength at the peak frequency can be large enough to be detected at future spacebased gravitational interferometers such as eLISA, DECIGO and BBO. Predicted deviations in the various Higgs boson couplings are also evaluated at the zero temperature, and are shown to be large enough too. Therefore, in this model strongly first order electroweak phase transition can be tested by the combination of the precision study of various Higgs boson couplings at the LHC, the measurement of the triple Higgs boson coupling at future lepton colliders and the shape of the spectrum of gravitational wave detectable at future gravitational interferometers. (C) 2017 The Authors. Published by Elsevier B.V 

Publication at kias
NUMBER  P16036 
AUTHOR  Ko, Pyungwon 
TITLE  Revisiting T2KK and T2KO physics potential and nu mu(nu)overbar mu beam ratio 
ARCHIVE  arXiv:1605.02368 
FILE  
JOURNAL  EUROPEAN PHYSICAL JOURNAL C, 2017 
ABSTRACT  We revisit the sensitivity study of the Tokaito KamiokaandKorea (T2KK) and TokaitoKamiokaandOki (T2KO) proposals where a water Cerenkov detector with the 100 kton fiducial volume is placed in Korea (L = 1000 km) and Oki island (L = 653 km) in Japan, respectively, in addition to the SuperKamiokande for determination of the neutrino mass hierarchy and leptonic CP phase (delta(CP)). We systematically study the running ratio of the nu(mu) and (nu) over bar (mu) focusing beams with dedicated background estimation for the nu(e) appearance and nu(mu) disappearance signals, especially improving treatment of the neutralcurrent pi(0) backgrounds. Using a nu(mu)(nu) over bar (mu) beam ratio between 3: 2 and 2.5: 2.5 (in units of 10(21)POT with the proton energy of 40 GeV), the masshierarchy determination with the median sensitivity of 35 sigma by the T2KK and 14 sigma by the T2KO experiment are expected when sin(2) theta(23) = 0.5, depending on the masshierarchy pattern and CP phase. These sensitivities are enhanced (reduced) by 3040% in Delta chi(2) when sin(2) theta(23) = 0.6 (0.4). The CP phase is measured with the uncertainty of 20 degrees50 degrees by theT2KKandT2KOusing the nu(mu)(nu) over bar (mu) focusing beam ratio between 3.5: 1.5 and 1.5: 3.5. These findings indicate that inclusion of the (nu) over bar mu focusing beam improves the sensitivities of the T2KK and T2KO experiments to both the masshierarchy determination and the leptonic CP phase measurement simultaneously with the preferred beam ratio being between 3: 22.5: 2.5 (x10(21)POT). 

Publication at kias
NUMBER  P16027 
AUTHOR  Ko, P.,Kang, Zhaofeng,Li, Jinmian 
TITLE  Asymmetric dark matter bound state 
ARCHIVE  arXiv:1602.08816 
FILE  
JOURNAL  PHYSICAL REVIEW D, 2017 
ABSTRACT  We propose an interesting framework for asymmetric scalar dark matter (ADM), which has novel collider phenomenology in terms of an unstable ADM bound state (ADMonium) produced via Higgs portals. ADMonium is a natural consequence of the basic features of ADM: the (complex scalar) ADM is charged under a dark local U(1)(d) symmetry which is broken at a low scale and provides a light gauge boson X. The dark gauge coupling is strong and then ADM can annihilate away into Xpair effectively. Therefore, the ADM can form a bound state due to its large selfinteraction via X mediation. To explore the collider signature of ADMonium, we propose that ADM has a twoHiggs doublet portal. The ADMonium can have a sizable mixing with the heavier Higgs boson, which admits a large cross section of ADMonium production associated with b (b) over bar. The resulting signature at the LHC depends on the decays of X. In this paper we consider a case of particular interest: pp > b (b) over bar + ADMonium followed by ADMonium > 2X > 2e(+)e() where the electrons are identified as (un)converted photons. It may provide a competitive explanation to heavy diphoton resonance searches at the LHC. 

Publication at kias
NUMBER  P16076 
AUTHOR  Ko, P.,Li, Jinmian 
TITLE  Interference effects of two scalar boson propagators on the LHC search for the singlet fermion DM 
ARCHIVE  arXiv:1610.03997 
FILE  
JOURNAL  PHYSICS LETTERS B, 2017 
ABSTRACT  A gauge invariant UVcompletion for singlet fermion DM interacting with the standard model (SM) particles involves a new singlet scalar. Therefore the model contains two scalar mediators, mixtures of the SM Higgs boson and a singlet scalar boson. Collider phenomenology of the interference effect between these two scalar propagators is studied in this work. This interference effect can be either constructive or destructive in the DM production cross section depending on both singlet scalar and DM masses, and it will soften the final state jets in the full mass region. Applying the CMS monojet search to our model, we find the interference effect plays a very important role in the DM search sensitivity, and the DM production cross section of our model is more than one order of magnitude below the LHC sensitivity at current stage. (C) 2016 The Author(s). Published by Elsevier B.V. 

Publication at kias
NUMBER  Q16017 
AUTHOR  Ko, Pyungwon,Kim, Jinsu 
TITLE  Higgsportal assisted Higgs inflation with a sizeable tensortoscalar ratio 
ARCHIVE  1405.1635 
FILE  
JOURNAL  JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, 2017 
ABSTRACT  We show that the Higgs portal interactions involving extra dark Higgs field can save generically the original Higgs inflation of the standard model (SM) from the problem of a deep nonSM vacuum in the SM Higgs potential. Specifically, we show that such interactions disconnect the top quark pole mass from inflationary observables and allow multidimensional parameter space to save the Higgs inflation, thanks to the additional parameters (the dark Higgs boson mass m(phi), the mixing angle a between the SM Higgs H and dark Higgs Phi, and the mixed quartic coupling) affecting RGrunning of the Higgs quartic coupling. The effect of Higgs portal interactions may lead to a larger tensortoscalar ratio, 0.08 less than or similar to r less than or similar to 0.1, by adjusting relevant parameters in wide ranges of alpha and m(phi), some region of which can be probed at future colliders. Performing a numerical analysis we find an allowed region of parameters, matching the latest Planck data. 

Publication at kias
NUMBER  Q16012 
AUTHOR  Ko, P.,Yokoya, Hiroshi,Natale, Alexander 
TITLE  Simplified DM models with the full SM gauge symmetry: the case of tchannel colored scalar mediators 
ARCHIVE  arXiv:1605.07058 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2017 
ABSTRACT  The general strategy for dark matter (DM) searches at colliders currently relies on simpli fi ed models. In this paper, we propose a new t channel UVcomplete simpli fi ed model that improves the existing simpli fi ed DM models in two important respects: (i) we impose the full SM gauge symmetry including the fact that the lefthanded and the righthanded fermions have two independent mediators with two independent couplings, and (ii) we include the renormalization group evolution when we derive the e ff ective Lagrangian for DMnucleon scattering from the underlying UV complete models by integrating out the t channel mediators. The fi rst improvement will introduce a few more new parameters compared with the existing simpli fi ed DM models. In this study we look at the e ff ect this broader set of free parameters has on direct detection and the monoX + MET (X = jet, W; Z) signatures at 13TeV LHC while maintaining gauge invariance of the simplifi ed model under the full SM gauge group. We fi nd that the direct detection constraints require DM masses less than 10 GeV in order to produce phenomenologically interesting collider signatures. Additionally, for a fi xed monoW cross section it is possible to see very large di ff erences in the monojet cross section when the usual simpli fi ed model assumptions are loosened and isospin violation between RH and LH DMSM quark couplings are allowed. 

Publication at kias
NUMBER  P16002 
AUTHOR  Ko, P. 
TITLE  Diphoton excess at 750 GeV in leptophobic U(1) model inspired by E6 GUT 
ARCHIVE  arXiv:1601.00586 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2016 
ABSTRACT  We discuss the 750 GeV diphoton excess at the LHCA@13TeV in the framework of leptophobic U(1) model inspired by E6 grand unified theory (GUT). In this model, the Standard Model (SM) chiral fermions carry charges under extra U(1) gauge symmetry which is spontaneously broken by a U(1)charged singlet scalar (Phi)). In addition, extra quarks and leptons are introduced to achieve the anomaly free conditions, which is a natural consequence of the assumed E6 GUT. These new fermions are vectorlike under the SM gauge group but chiral under new U(1), and their masses come entirely from the nonzero vacuum expectation value of Phi through the Yukawa interactions. Then, the CPeven scalar h(Phi) from Phi can be produced at the LHC by the gluon fusion and decay to the diphoton via the one loop diagram involving the extra quarks and leptons, and can be identified as the origin of diphoton excess at 750 GeV. In this model, h(Phi), can decay into a pair of dark matter particles as well as a pair of scalar bosons, thereby a few tens of the decay width may be possible. 

Publication at kias
NUMBER  P16063 
AUTHOR  Ko, P.,Tang, Yong 
TITLE  Light dark photon and fermionic dark radiation for the Hubble constant and the structure formation 
ARCHIVE  1608.01083 
FILE  
JOURNAL  PHYSICS LETTERS B, 2016 
ABSTRACT  Motivated by the tensions in the Hubble constant H0 and the structure growth sigma(8) between Planckresults and other low redshift measurements, we discuss some cosmological effects of a dark sector model in which dark matter (DM) interacts with fermionic dark radiation (DR) through a light gauge boson (dark photon). Such kind of models are very generic in particle physics with a dark sector with dark gauge symmetries. The effective number of neutrinos is increased by delta Neff similar to 0.5 due to light dark photon and fermionic DR, thereby resolving the conflicts in H0. The elastic scattering between DM and DR induces suppression for DMs density perturbation, but without acoustic oscillations. For weaklyinteracting DM around 100GeV, the new gauge coupling should be similar to 10(4) to have sizable effect on matter power spectrum in order to relax the tension in s8. (C) 2016 The Author(s). Published by Elsevier B.V. 

Publication at kias
NUMBER  P16022 
AUTHOR  Ko, Pyungwon 
TITLE  Flavor SU (3) properties of beauty tetraquark states with three different light quarks 
ARCHIVE  arXiv:1603.02915 
FILE  
JOURNAL  PHYSICS LETTERS B, 2016 
ABSTRACT  Beauty tetraquark states X ((b) over barq q (q) over bar) composed of (b) over bar su (d) over bar, (b) over bar ds (u) over bar, and (b) over bar ud (s) over bar, are unique that all the four valence quarks are different. Although the claim of existence of the first two states by DO was not confirmed by data from LHCb, the possibility of such states still generated a lot of interests and should be pursued further. Nonobservation of X((b) over barqq (q) over bar) states by LHCb may be just due to a still lower production rate than the limit of LHCb or at some different mass ranges. In this work we use light quark SU(3) flavor symmetry as guideline to classify symmetry properties of beauty tetraquark states. The multiplets which contain states with three different light quarks must be one of (6) over bar or 15 of SU(3) representations. We study possible decays of such a tetraquark state into a B meson and a light pseudoscalar octet meson by constructing a leading order chiral Lagrangian, and also provide search strategies to determine whether a given tetraquark state of this type belongs to (6) over bar or 15. If X((b) over barqq (q) over bar) belongs to 15, there are new doubly charged tetraquark states (b) over bar uu (d) over bar and (b) over bar uu (s) over bar. (C) 2016 The Authors. Published by Elsevier B.V. 

Publication at kias
NUMBER  P16001 
AUTHOR  Ko, P. 
TITLE  Higgs precision study of the 750 GeV diphoton resonance and the 125 GeV standard model Higgs boson with Higgssinglet mixing 
ARCHIVE  arXiv:1512.07853 
FILE  
JOURNAL  PHYSICAL REVIEW D, 2016 
ABSTRACT  We interpret the potential observation of the 750 GeV diphoton resonance at the LHC in models, in which an SU(2) isospinsinglet scalar boson mixes with the standard model (SM) Higgs boson through an angle alpha. Allowing the singlet scalar boson to have renormalizable couplings to vectorlike leptons and quarks and introducing sizable decay width of the 750 GeV diphoton resonance into nonSMparticles such as dark matters, we can explain the large production cross section sigma(H2) x B(H2 > gamma gamma) as well as the apparent large total width of the boson without conflicts from the results obtained by previous global fits to the SM Higgs boson data. 

Publication at kias
NUMBER  P16045 
AUTHOR  Ko, Pyungwon,Hatanaka, Hisaki 
TITLE  AdS/QCD approach to the scaleinvariant extension of the standard model with a strongly interacting hidden sector 
ARCHIVE  arXiv:1606.02969 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2016 
ABSTRACT  In this paper, we revisit a scaleinvariant extension of the standard model (SM) with a strongly interacting hidden sector within AdS/QCD approach. Using the AdS/QCD, we reduce the number of input parameters to three, i.e. hidden pion decay constant, hidden pion mass and tan beta that is defined as the ratio of the vacuum expectation values (VEV) of the singlet scalar field and the SM Higgs boson. As a result, our model has sharp predictability. We perform the phenomenological analysis of the hidden pions which is one of the dark matter (DM) candidates in this model. With various theoretical and experimental constraints we search for the allowed parameter space and find that both resonance and nonresonance solutions are possible. Some typical correlations among various observables such as thermal relic density of hidden pions, Higgs boson signal strengths and DMnucleon cross section are investigated. We provide some benchmark points for experimental tests. 

Publication at kias
NUMBER  P16044 
AUTHOR  Ko, Pyungwon,Baek, Seungwon,Wu, Peiwen 
TITLE  Topphilic scalar Dark Matter with a vectorlike fermionic top partner 
ARCHIVE  arXiv:1606.00072 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2016 
ABSTRACT  We consider a simple extension of the Standard Model with a scalar topphilic Dark Matter (DM) S coupling, apart from the Higgs portal, exclusively to the righthanded top quark t (R) and a colored vectorlike top partner T with a Yukawa coupling y (ST) which we call the topVL portal. When the Higgs portal is closed and y (ST) is perturbative (less than or similar to 1), T S > (W (+) b, gt), SS > t (t) over bar and T (T) over bar > (q (q) over bar, gg) provide the dominant (co) annihilation contributions to obtain Omega(DM) h (2) similar or equal to 0.12 in light, medium and heavy DM mass range, respectively. However, large yST similar to O(10) can make SS > gg dominate via the loopinduced coupling C (SSgg) in the m (S) < m (t) region. In this model it is the C (SSgg) coupling that generates DMnucleon scattering in the direct detection, which can be large and simply determined by Omega(DM) h (2) similar or equal to 0.12 when SS > gg dominates the DM annihilation. The current LUX results can exclude the SS > gg dominating scenario and XENON1T experiment may further test y (ST) greater than or similar to 1, and 0.5 less than or similar to y (ST) less than or similar to 1 may be covered in the future LUXZP experiment. The current indirect detection results from Fermi gammaray observations can also exclude the SS > gg dominating scenario and are sensitive to the heavy DM mass region, of which the improved sensitivity by one order will push DM mass to be above 400, 600, 1000 GeV for y (ST) = 0.3, 0.5, 1.0, respectively. T (T) over bar pair produced at the hadron collider will decay 100% into t (t) over bar + is not an element of(T) signal when kinematically open. The latest ATLAS 13 TeV 13.2 fb(1) data can excluded m (T) between 300 (650) and 1150 (1100) GeV for m (S) =40 (400) GeV and the exclusion region can reach up to m(S) similar to 500 GeV. 

Publication at kias
NUMBER  P15057 
AUTHOR  Ko, P.,Nomura, Takaaki 
TITLE  SU(2)(L) x SU(2)(R) minimal dark matter with 2 TeV W 
ARCHIVE  arXiv:1510.07872 
FILE  
JOURNAL  PHYSICS LETTERS B, 2016 
ABSTRACT  We construct the minimal dark matter models in the leftright symmetric extensions of the standard model (SM), where the gauge symmetry SU(3)(C) x SU(2)(L) x SU(2)(R) x U(1)(BL) is broken into its subgroup SU(3)(C) x U(1)(em) by nonzero VEVs of a SU(2)(R) doublet HR and a SU(2)(L) x SU(2)(R) bidoublet H. A possible candidate of dark matter is explored in the framework of minimal dark matter considering SU(2)(L,R) multiplet scalar bosons and fermions. Then we focus on SU(2)(R) quintuplet fermions with B  L charges 0, 2 and 4 as the minimal dark matter candidates and investigate their phenomenology. We show that the dark matter in the model can provide observed relic density with 2 TeV W boson which is motivated by the ATLAS diboson excess and CMS eejj excess. The possible mass of dark matter is predicted for each B  L charge. We then estimate the scattering cross section of dark matter with nucleon and production cross section of charged components in the quintuplets at the LHC. (C) 2015 The Authors. Published by Elsevier B.V. 

Publication at kias
NUMBER  P16018 
AUTHOR  Ko, P.,Nomura, Takaaki 
TITLE  Confronting a new threeloop seesaw model with the 750 GeV diphoton excess 
ARCHIVE  arXiv:1602.07214 
FILE  
JOURNAL  PHYSICAL REVIEW D, 2016 
ABSTRACT  We propose a new type of radiative neutrino model with a local dark U(1) symmetry, where neutrino masses are induced at the threeloop level, and discuss the muon anomalous magnetic moment and dark matter candidates therein. By allowing hypercharges larger than 3/2 for new fields that contribute to the neutrino masses and making them decay into the standardmodel fields appropriately, we introduce a lot of new particles with multiple electrical charges in a natural manner. As a byproduct, we can accommodate the 750 GeV diphoton excess depending on the hypercharge quantum numbers of new fields responsible for the neutrino masses at the threeloop level. 

Publication at kias
NUMBER  P16006 
AUTHOR  Ko, P.,Nomura, Takaaki 
TITLE  Dark sector shining through 750 GeV dark Higgs boson at the LHC 
ARCHIVE  arXiv:1601.02490 
FILE  
JOURNAL  PHYSICS LETTERS B, 2016 
ABSTRACT  We consider a dark sector with SU(3)(C) x U(1)(Y) x U(1)(X) and three families of dark fermions that are chiral under dark U(1)(X) gauge symmetry, whereas scalar dark matter Xis the SM singlet. U(1)(X) dark symmetry is spontaneously broken by nonzero VEV of dark Higgs field , generating the masses of dark fermions and dark photon Z. The resulting dark Higgs boson phi can be produced at the LHC by dark quark loop (involving 3 generations) and will decay into a pair of photon through charged dark fermion loop. Its decay width can be easily similar to 45 GeV due to its possible decays into a pair of dark photon, which is not strongly constrained by the current LHC searches pp > phi > ZZ followed by Z decays into the SM fermion pairs. The scalar DM can achieve thermal relic density without conflict with direct detection bound or the invisible phi decay into a pair of DM. (C) 2016 The Author(s). Published by Elsevier B.V. 

Publication at kias
NUMBER  Q16009 
AUTHOR  Ko, P.,Yokoya, Hiroshi 
TITLE  Search for Higgs portal DM at the ILC 
ARCHIVE  arXiv:1603.04737 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2016 
ABSTRACT  Higgs portal dark matter (DM) models are simple interesting and viable DM models. There are three types of the models depending on the DM spin: scalar, fermion and vector DM models. In this paper, we consider renormalizable, unitary and gauge invariant Higgs portal DM models, and study how large parameter regions can be surveyed at the International Linear Collider (ILC) experiment at root s = 500 GeV. For the Higgs portal singlet fermion and vector DM cases, the force mediator involves two scalar propagators, the SMlike Higgs boson and the dark Higgs boson. We show that their interference generates interesting and important patterns in the monoZ plus missing ET signatures at the ILC, and the results are completely different from those obtained from the Higgs portal DM models within the effective field theories. In addition, we show that it would be possible to distinguish the spin of DM in the Higgs portal scenarios, if the shape of the recoilmass distribution is observed. We emphasize that the interplay between these collider observations and those in the direct detection experiments has to be performed in the model with renomalizability and unitarity to combine the model analyses in different scales. 

Publication at kias
NUMBER  P15029 
AUTHOR  Ko, P.,Baek, Seungwon 
TITLE  Beyond the dark matter effective field theory and a simplified model approach at colliders 
ARCHIVE  arXiv:1506.06556 
FILE  
JOURNAL  PHYSICS LETTERS B, 2016 
ABSTRACT  Direct detection of and LHC search for the singlet fermion dark matter (SFDM) model with Higgs portal interaction are considered in a renormalizable model where the full Standard Model (SM) gauge symmetry is imposed by introducing a singlet scalar messenger. In this model, direct detection is described by an effective operator m(q)(q) over barq (chi) over bar chi as usual, but the full amplitude for monojet + is not an element of(T) involves two intermediate scalar propagators, which cannot be seen within the effective field theory (EFT) or in the simplified model without the full SM gauge symmetry. We derive the collider bounds from the ATLAS monojet + is not an element of(T) as well as the CMS t (t) over bar + is not an element of(T) data, finding out that the bounds and the interpretation of the results are completely different from those obtained within the EFT or simplified models. It is pointed out that it is important to respect unitarity, renormalizability and local gauge invariance of the SM. (C) 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license 

Publication at kias
NUMBER  
AUTHOR  Ko, P.,Kang, Zhaofeng 
TITLE  New avenues to heavy righthanded neutrinos with pair production at hadronic colliders 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D, 2016 
ABSTRACT  In many models incorporating the typeI seesaw mechanism, the righthanded neutrino (N) couples to heavy vector/scalar bosons and thereby has resonant pair production. It has barely received attention thus far; however, it may provide the best avenue to probe TeV scale N without requiring anomalously large mixing between N and the active neutrino nu(L). In this paper we explore the discovery prospects of (mainly heavy) N pair production at the 14 TeV LHC and future 100 TeV pp collider, based on the three signatures: (1) trilepton from N (> lW(l)) N (> lW(h)) with Wl/h being the leptonically/hadronically decaying W; (2) boosted diHiggs boson plus ET from N (> nu(L)h) N (> nu(L)h); (3) a single boosted Higgs boson with leptons and ET from N (> lW(l)) N (> nu(L)h). At the 100 TeV collider, we also consider the situation when the Higgs boson is overboosted, thus losing its jet substructure. Interpreting our tentative results in the benchmark model, the local BL model, we find that the (multi) TeV scale N can be probed at the (100) 14 TeV colliders. 

Publication at kias
NUMBER  P16053 
AUTHOR  Ko, P.,Nomura, Takaaki 
TITLE  Phenomenology of dark matter in chiral U(1)(X) dark sector 
ARCHIVE  arXiv:1607.06218 
FILE  
JOURNAL  PHYSICAL REVIEW D, 2016 
ABSTRACT  We consider dark matter physics in a model for the dark sector with extra dark U(1)(X) gauge symmetry. The dark sector is composed of exotic fermions that are charged under both dark U(1)(X) and the standard model SU(3)(C) xU(1)(Y) gauge groups, as well as standard model singlet complex scalars Phi and X with nonzero U(1)(X) charge. In this model, there are two dark matter candidatesa scalar and a fermionboth of which are stabilized by accidental Z(2) symmetry. Their thermal relic density, and direct and indirect detection constraints are discussed in detail and we search for the parameter space of the model accommodating dark matter observations. We also discuss constraints from diphoton resonance searches associated with the scalar field which breaks the dark U(1)(X), in a way consistent with dark matter physics. In addition, implications for collider physics are discussed, focusing on the production cross section of the scalar boson. 

Publication at kias
NUMBER  P15028 
AUTHOR  Ko, P.,Kang, Zhaofeng 
TITLE  New Physics Opportunities in the Boosted DiHiggsBoson Plus Missing Transverse Energy Signature 
ARCHIVE  arXiv:1504.04128 
FILE  
JOURNAL  PHYSICAL REVIEW LETTERS, 2016 
ABSTRACT  The Higgs field in the standard model may couple to new physics sectors related to dark matter and/or massive neutrinos. In this Letter we propose a novel signature, the boosted diHiggsboson plus ET (which is either a dark matter or neutrino), to probe those new physics sectors. In a large class of models, in particular, the supersymmetric standard models and low scale seesaw mechanisms, this signature can play a key role. The signature has a clear background, and at the root s = 14 TeV high luminosity LHC, we can probe it with a production rate as low as similar to 0.1 fb. We apply it to benchmark models, supersymmetry in the binoHiggsino limit, the canonical seesaw model, and the little Higgs model, finding that the masses of the Higgsino, righthanded neutrino, and heavy vector boson can be probed up to similar to 500, 650, and 900 GeV, respectively. 

Publication at kias
NUMBER  P15027 
AUTHOR  Ko, P.,Tang, Yong 
TITLE  Dark Higgs channel for Fermi GeV gammaray excess 
ARCHIVE  arXiv:1504.03908 
FILE  
JOURNAL  JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, 2016 
ABSTRACT  Dark Higgs is very generic in dark matter models where DM is stabilized by some spontaneously broken dark gauge symmetries. Motivated by tentative GeV scale gammaray excess from the galactic center (GC), we investigate a scenario where a pair of dark matter X annihilates into a pair of dark Higgs H2, which subsequently decays into standard model particles through its mixing with SM Higgs boson. Besides the twobody decay of H2, we also include multibody decay channels of the dark Higgs. We find that the bestfit point is around MX similar or equal to 95.0 GeV, MH2 similar or equal to 86.7 GeV, sigma nu similar or equal to 4.0 x 10(26)cm(3)/s and gives a pvalue similar or equal to 0.40. Implication of this result is described in the context of dark matter models with dark gauge symmetries. Since such a dark Higgs boson is very difficult to produce at colliders, indirect DM detections of cosmic gammarays could be an important probe of dark sectors, complementary to collider searches. 

Publication at kias
NUMBER  
AUTHOR  Ko, P. 
TITLE  Bounds on Higgsportal models from the LHC Higgs data 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2015 
ABSTRACT  In a number of Higgsportal models, an SU(2) isospinsinglet scalar boson generically appears at the electroweak scale and can mix with the Standard Model (SM) Higgs boson with a mixing angle alpha. This singlet scalar boson can have renormalizable couplings to a pair of dark matter particles, vectorlike leptons or quarks, or new gauge bosons, thereby modifying the Higgs signal strengths in a nontrivial way. In this work, we perform global fits to such models using the most updated LHC Higgsboson data and discuss the corresponding implications on Higgsportaltype models. In particular we find that the current LHC Higgsboson data slightly favors the SM over the Higgsportal singletscalar models, which has to be further examined using the upcoming LHC Higgsboson data. Finally, without nonSM particles contributing to the H gamma gamma and Hgg vertices, the Higgsportal models are constrained as follows: cos alpha greater than or similar to 0.86 and Delta Gamma(tot) less than or similar to 1.24 MeV at 95% confidence level (CL). 

Publication at kias
NUMBER  P15006 
AUTHOR  Ko, P.,Yu, Chaehyun 
TITLE  Higgs and dark matter physics in the typeII twoHiggsdoublet model inspired by E6 GUT 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2015 
ABSTRACT  We study Higgs and dark matter physics in the typeII twoHiggsdoublet model (2HDM) with an extra U(1)(H) gauge symmetry, inspired by the E6 grand unified theory (GUT). From the viewpoint of the bottomup approach, the additional U(1)(H) gauge symmetry plays a crucial role in avoiding the treelevel flavor changing neutral currents mediated by neutral Higgs bosons in general 2HDMs. In the model with U(1)(H) gauge symmetry, which has TypeII Yukawa couplings, we have to introduce additional chiral fermions that are charged under the U(1)(H) gauge symmetry as well as under the StandardModel (SM) gauge symmetry in order to cancel chiral gauge anomalies. For the U(1)(H) charge assignment and the extra matters, we adopt the ones inspired by the E6 GUT: the extra quarklike and leptonlike fermions with the nontrivial U(1)(H) charges. We discuss their contributions to the physical observables, such as the measurements of Higgs physics and electroweak interactions, and investigate the consistency with the experimental results. Furthermore, we could find extra neutral particles like the SM neutrinos after the electroweak symmetry breaking, and they could be stable, because of the remnant symmetry after U(1)(H) symmetry breaking. We also discuss the thermal relic density and the (in)directdetections of this dark matter candidate. 

Publication at kias
NUMBER  
AUTHOR  Ko, P.,Tang, Yong 
TITLE  IceCube events from heavy DM decays through the righthanded neutrino portal 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B, 2015 
ABSTRACT  The recently observed IceCube PeV events could be due to heavy dark matter (DM) decay. In this paper, we propose a simple DM model with extra U(1)(X) gauge symmetry and bridge it with standard model particles through heavy righthanded neutrino. The Dirac fermion DM chi with mass similar to 5PeV can dominantly decay into a dark Higgs (phi), the SM Higgs (h) and a neutrino (nu). If the lifetime of chi is similar to O(10(28)) s, the resulting neutrino flux can fit data consistently. The neutrino flux from chi >phi h nu in our model is softer than the one predicted from chi >nu h, for example. We also discuss a possible mechanism to produce DM with the right relic abundance. (C) 2015 The Authors. Published by Elsevier B.V. 

Publication at kias
NUMBER  P14076 
AUTHOR  Ko, P.,Tang, Young 
TITLE  AMS02 positron excess from decaying fermion DM with local dark gauge symmetry 
ARCHIVE  arXiv:1410.7657 
FILE  
JOURNAL  PHYSICS LETTERS B, 2015 
ABSTRACT  Positron excess observed by PAMELA, Fermi and AMS02 may be due to dark matter (DM) pair annihilation or decay dominantly into muons. In this paper, we consider a scenario with thermal fermionic DM (chi) with mass similar to O(12) TeV decaying into a dark Higgs (phi) and an active neutrino (nu(a)) instead of the SM Higgs boson and nu(a). We first present a renormalizable model for this scenario with local dark U(1)(X) gauge symmetry, in which the DM chi can be thermalized by Higgs portal and the gauge kinetic mixing. Assuming the dark Higgs (phi) mass is in the range 2m(mu) < m(phi) < 2m(pi)0, the positron excess can be fit if a proper background model is used, without conflict with constraints from antiproton and gammaray fluxes or direct detection experiments. Also, having such a light dark Higgs, the selfinteraction of DM can be enhanced to some extent, and three puzzles in the CDM paradigm can be somewhat relaxed. (C) 2015 The Authors. Published by Elsevier B. V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). 

Publication at kias
NUMBER  P17135 
AUTHOR  Ko, P.,Baek, Seungwon,Park, WanIl 
TITLE  Local Z(2) scalar dark matter model confronting galactic GeVscale gammaray 
ARCHIVE  arXiv:1407.6588 
FILE  
JOURNAL  PHYSICS LETTERS B, 2015 
ABSTRACT  We present a scalar dark matter (DM) model where DM (XI) is stabilized by a local Z(2) symmetry originating from a spontaneously broken local dark U(1)(X). Compared with the usual scalar DM with a global Z(2) symmetry, the local Z(2) model possesses three new extra fields, dark photon 21, dark Higgs phi and the excited partner of scalar DM (XR), with the kinetic mixing and Higgs portal interactions dictated by local dark gauge invariance. The resulting model can accommodate thermal relic density of scalar DM without conflict with the invisible Higgs branching ratio and the bounds from DM direct detections, thanks to the newly opened channels, XIXI > ZZ, phi phi. In particular, due to the new particles, the GeV scale gammaray excess from the Galactic Center (GC) can be originated from the decay of dark Higgs boson which is produced in DM annihilations. (C) 2015 The Authors. Published by Elsevier B.V. 

Publication at kias
NUMBER  P14025 
AUTHOR  Ko, P.,Kang, Zhaofeng 
TITLE  Natural Xray lines from the low scale supersymmetry breaking 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B, 2015 
ABSTRACT  In the supersymmetric models with low scale supersymmetry (SUSY) breaking where the gravitino mass is around keV, we show that the 3.5 keV Xray lines can be explained naturally through several different mechanisms: (I) a keV scale dark gaugino plays the role of sterile neutrino in the presence of bilinear Rparity violation. Because the light dark gaugino obtains Majorana mass only via gravity mediation, it is a decaying warm dark matter (DM) candidate; (II) the compressed cold DM states, whose mass degeneracy is broken by gravity mediated SUSY breaking, emit such a line via the heavier one decay into the lighter one plus photon(s). A highly supersymmetric dark sector may readily provide such kind of system; (III) the light axino, whose mass again is around the gravitino mass, decays to neutrino plus gamma in the Rparity violating SUSY. Moreover, we comment on dark radiation from dark gaugino. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license. 

Publication at kias
NUMBER  P14074 
AUTHOR  Ko, P.,Tang, Yong 
TITLE  Galactic center gammaray excess in hidden sector DM models with dark gauge symmetries: local Z(3) symmetry as an example 
ARCHIVE  arXiv:1407.5492 
FILE  
JOURNAL  JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, 2015 
ABSTRACT  We show that hidden sector dark matter (DM) models with local dark gauge symmetries make a natural playground for the possible gammaray excess from the galactic center (GC). We first discuss in detail the GC gammaray excess in a scalar dark matter (DM) model with local Z(3) symmetry which was recently proposed by the present authors. Within this model, scalar DM with mass 3070 GeV is allowed due to the newlyopened (semi)annihilation channels of a DM pair into dark Higgs phi and/or dark photon Z pair, and the gammaray spectrum from the GC can be fit within this model. Then we argue that the GC gamma ray excess can be easily accommodated within hidden sector dark matter models where DM is stabilized by local gauge symmetries, due to the presence of dark Higgs (and also dark photon for Abelian dark gauge symmetry). 

Publication at kias
NUMBER  P15007 
AUTHOR  Ko, P.,Kang, Zhaofeng 
TITLE  Accidental dark matter: Case in the scale invariant local B  L model 
ARCHIVE  arXiv:1502.00508 
FILE  
JOURNAL  PHYSICAL REVIEW D, 2015 
ABSTRACT  We explore the idea of accidental dark matter (aDM) stability in the scale invariant local U(1)(BL) model, which is a theory for neutrino and at the same time radiatively breaks scale invariance via quantum mechanical dynamics in the U(1)(BL) sector. A real singlet scalar can be accidental DM with an accidental Z(2), by virtue of both extended symmetries. A U(1)(BL) charged complex scalar can also be a viable accidental DM due to an accidental (or remanent) Z(3). They can reproduce correct relic density via the annihilations through the conventional Higgs portal or dark Higgs portal. The dark Higgs portal scenario is in tension with the LHC bound on Z(BL), and only heavy DM of a few TeVs can have correct relic density. In particular, DM may trigger classical scale invariance spontaneous breaking. The situation is relaxed significantly in the Z(3) case due to the effective semiannihilation mode, and then light DM can be accommodated easily. In addition, the Z(3) model can accommodate the GeV scale gammaray excess from the Galactic center via semiannihilation into pseudoGoldstone boson. The best fit is achieved at a DM about 52 GeV, with an annihilation cross section consistent with the thermal relic density. The invisible Higgs branching ratio is negligible because the Higgs portal quartic coupling is very small lambda(h phi) less than or similar to 10(3). 

Publication at kias
NUMBER  P14026 
AUTHOR  Ko, P.,Tang, Yong 
TITLE  nu Lambda MDM: A model for sterile neutrino and dark matter reconciles cosmological and neutrino oscillation data after BICEP2 
ARCHIVE  arXiv:1404.0236 
FILE  
JOURNAL  PHYSICS LETTERS B, 2014 
ABSTRACT  We propose an ultraviolet complete theory for cold dark matter (CDM) and sterile neutrinos that can accommodate both cosmological data and neutrino oscillation experiments within 1 sigma level. We assume a new U(1)(X) dark gauge symmetry which is broken at similar to O(MeV) scale resulting light dark photon. Such a light mediator for DMs selfscattering and scatteringoff sterile neutrinos can resolve three controversies for cold DM on small cosmological scales: cusp vs. core, toobigtofail and missing satellites. We can also accommodate similar to O(1) eV scale sterile neutrinos as the hot dark matter (HDM) and can fit some neutrino anomalies from neutrino oscillation experiments within 1 sigma. Finally, the right amount of HDM can make a sizable contribution to dark radiation, and also helps to reconcile the tension between the data on the tensortoscalar ratio reported by Planck and BICEP2 Collaborations. (C) 2014 The Authors. Published by Elsevier B.V. 

Publication at kias
NUMBER  P14030 
AUTHOR  Ko, P.,Yu, Chaehyun 
TITLE  Dark matter and dark force in the typeI inert 2HDM with local U(1)(H) gauge symmetry 
ARCHIVE  1405.2138 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2014 
ABSTRACT  We discuss dark matter (DM) physics in the TypeI inert twoHiggsdoublet model (2HDM) with local U(1) H Higgs gauge symmetry, which is assigned to the extra Higgs doublet in order to avoid the Higgsmediated flavor problems. In this gauged inert DM setup, a U(1)(H)charged scalar Phi is also introduced to break U(1)(H) spontaneously through its nonzero vacuum expectation value (VEV), , and then the remnant discrete subgroup appears according to the U(1)(H) charge assignment of Phi. The U(1)(H)charged Higgs doublet does not have Yukawa couplings with the StandardModel (SM) fermions, and its lightest neutral scalar component H is stable because of the remnant discrete symmetry. In order to suppress a too large Zexchange diagram contribution in DM direct detection experiments, we have to introduce a nonrenormalizable operator which can be generated by integrating out an extra heavy scalar. With these new particles contents, we first investigate the constraint on the U(1)(H) gauge interaction, especially through the kinetic and mass mixing between the SM gauge bosons and the extra gauge boson. Then we discuss dark matter physics in our 2HDM: thermal relic density, and direct/indirect detections of dark matter. The additional U(1) (H) gauge interaction plays a crucial role in reducing the DM thermal relic density. The most important result within the inert DM model with local U(1)(H) symmetry is that similar to O(10) GeV dark matter scenario, which is strongly disfavored in the usual Inert Doublet Model (IDM) with Z(2) symmetry, is revived in our model because of newly open channels, HH > Z(H)Z(H), Z(H)Z. Exotic Higgs decays, h > Z(H)Z(H), ZZ(H), would be distinctive signatures of the inert 2HDM with local U(1)(H) symmetry. 

Publication at kias
NUMBER  P13060 
AUTHOR  Ko, P.,Baek, Seungwon,Park, WanIl 
TITLE  Hidden sector monopole, vector dark matter and dark radiation with Higgs portal 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, 2014 
ABSTRACT  We show that the t HooftPolyakov monopole model in the hidden sector with Higgs portal interaction makes a viable dark matter model, where monopole and massive vector dark matter (VDM) are stable due to topological conservation and the unbroken subgroup U(1)(X). We show that, even though observed CMB data requires the dark gauge coupling to be quite small, a right amount of VDM thermal relic can be obtained via schannel resonant annihilation for the mass of VDM close to or smaller than the half of SM higgs mass, thanks to Higgs portal interaction. Monopole relic density turns out to be several orders of magnitude smaller than the observed dark matter relic density. Direct detection experiments, particularly, the projected XENON1T experiment, may probe the parameter space where the dark Higgs is lighter than less than or similar to 50 GeV. In addition, the dark photon associated with the unbroken U(1)(X) contributes to the radiation energy density at present, giving Delta Neff(nu) similar to 0.1 as the extra relativistic neutrino species. 

Publication at kias
NUMBER  P12056 
AUTHOR  Ko, P.,Baek, Seungwon,Senahaa, Eibun,Okada, Hiroshi 
TITLE  Can ZeeBabu model implemented with scalar dark matter explain both FermiLAT 130 GeV gammaray excess and neutrino physics? 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2014 
ABSTRACT  We extend the ZeeBabu model for the neutrino masses and mixings by first incorporating a scalar dark matter X with Z(2) symmetry and then X and a dark scalar phi with global U(1) symmetry. In the latter scenario the singly and doubly charged scalars that are new in the ZeeBabu model can explain the large annihilation cross section of a dark matter pair into two photons as hinted by the recent analysis of the Fermi gammaray space telescope data. These new scalars can also enhance the B(H >gamma gamma), as the recent LHC results may suggest. The dark matter relic density can be explained. The direct detection rate of the dark matter is predicted to be about one order of magnitude down from the current experimental bound in the first scenario. 

Publication at kias
NUMBER  P14034 
AUTHOR  Ko, P.,Baek, Seungwon,Park, WanIl 
TITLE  Invisible Higgs decay width versus dark matter direct detection cross section in Higgs portal dark matter models 
ARCHIVE  1405.3530 
FILE  
JOURNAL  PHYSICAL REVIEW D, 2014 
ABSTRACT  The correlation between the invisible Higgs branching ratio (Bh(inv)) versus dark matter (DM) direct detection cross section (sigma(SI)(p)) in Higgs portal singlet fermion DM (SFDM) or vector DM (VDM) models is usually presented in the effective field theory (EFT) framework. In this paper, we derive the explicit expressions for this correlation within UV completions of SFDM and VDM models with Higgs portals, and we discuss the limitations of the EFT approach. We show that there are at least two additional hidden parameters in sigma(SI)(p) in the UV completions: the singletlike scalar mass m(2) and its mixing angle alpha with the SM Higgs boson (h). In particular, if the singletlike scalar is lighter than the SM Higgs boson (m(2) < m(h) cos alpha/root 1+cos(2)alpha) the collider bound becomes weaker than the one based on EFT. 

Publication at kias
NUMBER  P14029 
AUTHOR  Ko, P.,Park, WamIl,Tang, Yong 
TITLE  Higgs portal vector dark matter for GeV scale gammaray excess from galactic center 
ARCHIVE  1404.5257 
FILE  
JOURNAL  JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, 2014 
ABSTRACT  We show that the GeV scale yray excess from the direction of the Galactic Center can be naturally explained by the pair annihilation of Abelian vector dark matter (VDM) into a pair of dark Higgs bosons (VV > phi phi), followed by the subsequent decay of phi into b (b) over bar or tau(tau) over bar. All the processes are described by a renormalizable VDM model with the Higgs portal, which is naturally flavordependent. Some parameter space of this scenario can be tested at the near future direct dark matter search experiments such as LUX and XENON1T. 

Publication at kias
NUMBER  
AUTHOR  Jung, Sunghoon,Yu, Chaehyun,Yoon, Yeo Woong,Ko, P. 
TITLE  Renormalization groupinduced phenomena of top pairs from fourquark effective operators 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2014 
ABSTRACT  We study the renormalization group(RG) evolution of fourquark operators that contribute to the top pair production. In particular, we focus on the cases in which certain observables are first induced from the oneloop RG while being absent at treelevel. From the operator mixing pattern, we classify all such RGinduced phenomena and underlying models that can induce them. We then calculate the full oneloop QCD RG evolution as the leading estimator of the effects and address the question of which RGinduced phenomena have largest and observable effects. The answer is related to the color structure of QCD. The studied topics include the RGinduction of top asymmetries, polarizations and polarization mixings as well as issues arising at this order. The RGinduction of top asymmetries is further compared with the generation of asymmetries from QCD and QED at oneloop order. We finally discuss the validity of using the RG as the proxy of oneloop effects on the top pair production. As an aside, we clarify the oftenstudied relations between top pair observables. 

Publication at kias
NUMBER  P14028 
AUTHOR  Jung, Sunghoon,Yu, Chaehyun,Yoon, Yeo Woong,Ko, P. 
TITLE  Correlation of top asymmetries: Loop versus tree origins 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D, 2014 
ABSTRACT  We study the correlation of top asymmetries that are sensitive to the different origin of (a new contribution to) the total asymmetry: loop or treelevel origins. We find that both the size and the sign of the correlation between total and t (t) over barj inclusive asymmetries are inherently different depending on the origin. We demonstrate the correlation by using the colorsinglet Z and the pure axigluon taken as representative models of loop and treeinduced total asymmetries. We calculate the nexttoleading order QCD corrections to the Z and perform Monte Carlo event generation. The correlation is understood in the QCD eikonal approximation using its color structure. 

Publication at kias
NUMBER  P14009 
AUTHOR  Ko, P.,Baek, Seungwon,Park, WanIl,Tang, Yong 
TITLE  Indirect and direct signatures of Higgs portal decaying vector dark matter for positron excess in cosmic rays 
ARCHIVE  1402.2115 
FILE  
JOURNAL  JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, 2014 
ABSTRACT  We investigate the indirect signatures of the Higgs portal U(1)x vector dark matter (VDM) X mu from both its pair annihilation and decay. The VDM is stable at renormalizable level by Z(2) symmetry, and thermalized by Higgsportal interactions. It can also decay by some nonrenormalizable operators with very long lifetime at cosmological time scale. If dim6 operators for VDM decays are suppressed by 10(16) GeV scale, the lifetime of VDM with mass similar to 2 TeV is just right for explaining the positron excess in cosmic ray observed by PAMELA and AMS02 Collaborations. The VDM decaying into mu(+)mu() can fit the data, evading various constraints on cosmic rays. We give one UVcomplete model as an example. This scenario for Higgs portal decaying VDM with mass around similar to 2 TeV can be tested by DM direct search at XENON1T, and also at the future colliders by measuring the Higgs selfcouplings. 

Publication at kias
NUMBER  
AUTHOR  Jung, DongWon,Ko, P. 
TITLE  Higgsdilaton(radion) system confronting the LHC Higgs data 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B, 2014 
ABSTRACT  We consider the Higgsdilaton(radion) system using the trace of energymomentum tensor (Thi,) with the full Standard Model (SM) gauge symmetry G(SM) SU(3)(c) x SU(2)(L) x U(1)(Y), and find out that the resulting phenomenology for the Higgsdilaton(radion) system is distinctly different from the earlier studies based on the Tmu mu with the unbroken subgroup Hsm equivalent to SU(3)(c), x U(1)(em) of G(SM). After electroweak symmetry breaking (EWSB), the SM Higgs boson and dilaton(radion) will mix with each other, and there appear two Higgslike scalar bosons and the Higgsdilaton mixing changes the scalar phenomenology in interesting ways. The signal strengths for the gginitiated channels could be modified significantly compared with the SM predictions due to the QCD scale anomaly and the Higgsdilaton(radion) mixing, whereas anomaly contributions are almost negligible for other channels. We also discuss the selfcouplings and the signal strengths of the 126 GeV scalar boson in various channels and possible constraints from the extra light/heavy scalar boson. The Higgsdilaton(radion) system considered in this work has a number of distinctive features that could be tested by the upcoming LHC running and at the ILC. (C) 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.orsilicenses/4/3M). 

Publication at kias
NUMBER  P14010 
AUTHOR  Ko, P.,Tang, Yong 
TITLE  Selfinteracting scalar dark matter with local Z(3) symmetry 
ARCHIVE  1402.6449 
FILE  
JOURNAL  JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, 2014 
ABSTRACT  We construct a selfinteracting scalar dark matter (DM) model with local discrete Z(3) symmetry that stabilizes a weak scale scalar dark matter X. The model assumes a hidden sector with a local U(1)x dark gauge symmetry, which is broken spontaneously into Z(3) subgroup by nonzero VEV of dark Higgs field phi(X) ( not equal 0). Compared with global Z(3) DM models, the local Z(3) model has two new extra fields: a dark gauge field Z and a dark Higgs field (phi) (a remnant of the U(1)(X) breaking). After imposing various constraints including the upper bounds on the spinindependent direct detection cross section and thermal relic density, we find that the scalar DM with mass less than 125 GeV is allowed in the local Z(3) model, in contrary to the global Z(3) model. This is due to new channels in the DM pair annihilations open into Z and phi in the local Z(3) model. Most parts of the newly open DM mass region can be probed by XENON1T and other similar future experiments. Also if phi is light enough (a few MeV less than or similar to m(phi) less than or similar to O(100) MeV), it can generate a right size of DM selfinteraction and explain the astrophysical small scale structure anomalies. This would lead to exotic decays of Higgs boson into a pair of dark Higgs bosons, which could be tested at LHC and ILC. 

Publication at kias
NUMBER  P13055 
AUTHOR  Ko, P.,Yu, Chaehyun,Omura, Yuji 
TITLE  Higgs phenomenology in TypeI 2HDM with U(1)(H) Higgs gauge symmetry 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2014 
ABSTRACT  It is well known that generic twoHiggsdoublet models (2HDMs) suffer from potentially large Higgsmediated flavorchanging neutral current (FCNC) problem, unless additional symmetries are imposed on the Higgs fields thereby respecting the Natural Flavor Conservation Criterion (NFC) by Glashow and Weinberg. A common way to respect the NFC is to impose Z(2) symmetry which is softly broken by a dim2 operator. Another new way is to introduce local U(1)(H) Higgs flavor symmetry that distinguishes one Higgs doublet from the other. In this paper, we consider the Higgs phenomenology in TypeI 2HDMs with the U(1)(H) symmetry with the simplest U(1)(H) assignments that the SM fermions are all neutral under U(1)(H), and we make detailed comparison with the ordinary TypeI 2HDM. After imposing various constraints such as vacuum stability and perturbativity as well as the electroweak precision observables and collider search bounds on charged Higgs boson, we find that the allowed Higgs signal strengths in our model are much broader than those in the ordinary TypeI 2HDM, because of newly introduced U(1)(H)charged singlet scalar and U(1)(H) gauge boson. Still the ATLAS data on gg > h > gamma gamma cannot be accommodated. Our model could be distinguished from the ordinary 2HDM with the Z(2) symmetry in a certain parameter region and some channels. If the couplings of the new boson turn out to be close to those in the SM, it would be essential to search for extra U(1)(H) gauge boson and/or one more neutral scalar boson to distinguish two models. 

Publication at kias
NUMBER  P13023 
AUTHOR  Jung, Sunghoon,Ko, P. 
TITLE  Implications of LHC data on 125 GeV Higgslike boson for the Standard Model and its various extensions 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2013 
ABSTRACT  Recent data on 125 GeV Higgslike boson at the LHC start to constrain the electroweak symmetry breaking (EWSB) sector of the Standard Model (SM) and its various extensions. If one imposes the local gauge symmetry of the SM (SU(3)(c) x SU(2)(L) x U(1)(Y)) to any possible new physics scenarios, the SM Higgs properties will be modified by intrinsically two ways: by new physics either coupling directly to the SM Higgs boson h, or affecting indirectly the SM Higgs properties through the mixing of h with a SM singlet scalar s. (Here s is a singlet under the SM gauge group, but may be charged under a new gauge charge and can have nonrenormalizable couplings to nonSM particles.) The models of two Higgs doublets, extra sequential and mirror fermions belong to the first category, whereas the models with a hidden sector dark matter, extra vectorlike fermions and new charged vector bosons, which can enhance the diphoton rate of the SM Higgslike resonance, belong to the second category. We perform a global fit to data in terms of the effective Lagrangian description of two interaction eigenstates of scalar bosons, a SM Higgs and a singlet scalar, and their mixing. This framework is more suitable to study singletextended scenarios discussed above compared to other approaches based on the Lagrangian of mass eigenstates. With fairly modelindependent assumptions, the effective Lagrangian contains at most four free parameters still encompassing the majority of models in the literature. Interestingly, the SM gives the best fit if all data from ATLAS and CMS are used, whereas various singlet extensions can fit better to individual ATLAS or CMS data. Without further assumptions, an upper bound on the total width (or, nonstandard branching ratio) is generically obtained. Furthermore, the global fit based on our parameterization can be used to probe interactions of the singlet scalar if the singlet resides below 2m(W). 

Publication at kias
NUMBER  P13057 
AUTHOR  Ko, P.,Baek, Seungwon,Park, WanIl 
TITLE  Singlet portal extensions of the standard seesaw models to a dark sector with local dark symmetry 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2013 
ABSTRACT  Assuming (i) the seesaw mechanism works for neutrino masses and mixings, (i i) dark matter is absolutely stable due to unbroken U(1)(X) dark gauge symmetry, and (i i i) the singlet fields ((HH)Hdagger and NR) are portal to the dark sector, we construct a simple model which is consistent with all the cosmological observations as well as terrestrial experiments available as of now, including leptogenesis, extra dark radiation of similar to 8% (resulting in Neff = 3.130 the effective number of neutrino species), Higgs inflation, small and large scale structure formation, and current relic density of scalar dark matter (X). The electroweak vacuum of this model is stable up to Planck scale for m(H) = 125GeV without any other new physics. The Higgs signal strength is equal to one as in the standard model for unbroken U(1)(X) case with a scalar dark matter, but it could be less than one independent of decay channels if the dark matter is a dark sector fermion or if U(1)(X) is spontaneously broken, because of a mixing with a new neutral scalar boson in the models. Detailed study of Higgs properties at the LHC would shed light on the models described in this work. 

Publication at kias
NUMBER  P12082 
AUTHOR  Ko, P.,Baek, Seungwon,Senaha, Eibun,Park, WanIl 
TITLE  Higgs portal vector dark matter: revisited 
ARCHIVE  1212.2131 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2013 
ABSTRACT  We revisit the Higgs portal vector dark matter model including a hidden sector Higgs field that generates the mass of the vector dark matter. The model becomes renormalizable and has two scalar bosons, the mixtures of the standard model (SM) Higgs and the hidden sector Higgs bosons. The strong bound from direct detection such as XENON100 is evaded due to the cancellation mechanism between the contributions from two scalar bosons. As a result, the model becomes still viable in large range of dark matter mass, contrary to some claims in the literature. The Higgs properties are also affected, the signal strengths for the Higgs boson search being universally suppressed relative to the SM value, which could be tested at the LHC in the future. 

Publication at kias
NUMBER  P12084 
AUTHOR  Ko, P.,Yu, Chaehyun 
TITLE  B > D(*())tau nu and B > tau nu in chiral U(1) models with flavored multi Higgs doublets 
ARCHIVE  1212.4607 [hepph] 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2013 
ABSTRACT  We discuss semileptonic and leptonic B decays, B > D(*())tau nu and B > tau nu, in the chiral U(1) models which were proposed by the present authors in the context of the top forwardbackward asymmetry (A(FB)(t)) observed at the Tevatron. In these models, extra Higgs doublets with nonzero U(1) charges are required in order to make the realistic mass matrix for uptype quarks. Then the extra (pseudo)scalars contribute to A(FB)(t) with large flavorchanging Yukawa couplings involving top quark. The contribution of the charged Higgs to A(FB)(t) is negligible, but it may significantly affect B decays: especially, B > D(*())tau nu and B > tau nu. We investigate constraints on the B decays, based on the recent results in BaBar and Belle experiments, and discuss the possibility that the allowed parameter region in the B decays can achieve large A(FB)(t). 

Publication at kias
NUMBER  P12024 
AUTHOR  Ko, P.,Yu, Chaehyun,Omura, Yuji 
TITLE  Top A(FB) at the Tevatron vs. charge asymmetry at the LHC in chiral U(1) flavor models with flavored Higgs doublets 
ARCHIVE  1205.0407 
FILE  
JOURNAL  EUROPEAN PHYSICAL JOURNAL C, 2013 
ABSTRACT  We consider the top forwardbackward (FB) asymmetry at the Tevatron and top charge asymmetry at the LHC within chiral U(1) models with flavordependent U(1) charges and flavored Higgs fields, which were introduced in Ko et al. (J. High Energy Phys. 1201:147, 2012). In this model, one has to include the flavorchanging couplings of the Higgs bosons as well as the Z to the uptype quarks. The models could enhance not only the top forwardbackward asymmetry at the Tevatron, but also the top charge asymmetry at LHC, without too large samesign topquark pair production rates. Also the m(t (t) over bar) distribution at high m(t (t) over bar) shows less deviations from the SM predictions. We identify parameter spaces for the U(1) gauge boson and (pseudo) scalar Higgs bosons where all the experimental data could be accommodated, including the case with about 125 GeV Higgs boson, as suggested recently by ATLAS and CMS. 

Publication at kias
NUMBER  P12061 
AUTHOR  Ko, P.,Baek, Seungwon,Senaha, Eibun,Park, WanIl 
TITLE  Vacuum structure and stability of a singlet fermion dark matter model with a singlet scalar messenger 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2012 
ABSTRACT  We consider the issue of vacuum stability and triviality bound of the singlet extension of the Standard Model (SM) with a singlet fermion dark matter (DM). In this model, the singlet scalar plays the role of a messenger between the SM sector and the dark matter sector. This model has two Higgslike scalar bosons, and is consistent with all the data on electroweak precision tests, thermal relic density of DM and its direct detection constraints. We show that this model is stable without hitting Landau pole up to Planck scale for 125GeV Higgs boson. We also perform a comprehensive study of vacuum structure, and point out that a region where electroweak vacuum is the global minimum is highly limited. In this model, both Higgslike scalar bosons have reduced couplings to the SM weak gauge bosons and the SM fermions, because of the mixing between the SM Higgs boson and the singlet scalar. There is also a possibility of their invisible decay(s) into a pair of DMs. Therefore this model would be disfavored if the future data on the (sigma . B)(VV) or (sigma . B)(f (f) over bar) with V = gamma, W, Z and f = b, tau turn out larger than the SM predictions. 

Publication at kias
NUMBER  P11063 
AUTHOR  Ko, P.,Yu, Chaehyun,Omura, Yuji 
TITLE  A resolution of the flavor problem of two Higgs doublet models with an extra U(1)(H) symmetry for Higgs flavor 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B, 2012 
ABSTRACT  We propose to implement the Natural Flavor Conservation criterion in the two Higgs doublet model (2HDM) to an extra U(1)(H) gauge symmetry for Higgs flavor, assuming two Higgs doublets carry different U(1)(H) charges. Then one can easily avoid the treelevel FCNC from neutral Higgs mediations using local gauge symmetries, instead of softly broken ad hoc Z(2) symmetry, and the pseudoscalar boson could be eaten by extra Z(H) boson. Imposing the anomaly cancellation, we find that the U(1)(H) in the TypeII and TypeIV 2HDMs become leptophobic and leptophilic, respectively. For the TypeI case, U(1)(H) depends on two parameters, and some simple cases include U(1)(H) = U(1)(BL), U(1)(R), or U(1)(Y). We sketch qualitative phenomenology of these models. (C) 2012 Elsevier B.V. All rights reserved. 

Publication at kias
NUMBER  P11024 
AUTHOR  Ko, Pyungwon 
TITLE  Simplified models for LHC new physics searches 
ARCHIVE  arXiv:1105.2838 
FILE  
JOURNAL  JOURNAL OF PHYSICS GNUCLEAR AND PARTICLE PHYSICS, 2012 
ABSTRACT  This document proposes a collection of simplified models relevant to the design of newphysics searches at the Large Hadron Collider (LHC) and the characterization of their results. Both ATLAS and CMS have already presented some results in terms of simplified models, and we encourage them to continue and expand this effort, which supplements both signaturebased results and benchmark model interpretations. A simplified model is defined by an effective Lagrangian describing the interactions of a small number of new particles. Simplified models can equally well be described by a small number of masses and crosssections. These parameters are directly related to collider physics observables, making simplified models a particularly effective framework for evaluating searches and a useful starting point for characterizing positive signals of new physics. This document serves as an official summary of the results from the Topologies for Early LHC Searches workshop, held at SLAC in September of 2010, the purpose of which was to develop a set of representative models that can be used to cover all relevant phase space in experimental searches. Particular emphasis is placed on searches relevant for the first similar to 50500 pb(1) of data and those motivated by supersymmetric models. This note largely summarizes material posted at http://lhcnewphysics.org/, which includes simplified model definitions, Monte Carlo material, and supporting contacts within the theory community. We also comment on future developments that may be useful as more data is gathered and analyzed by the experiments. 

Publication at kias
NUMBER  P11042 
AUTHOR  Ko, P.,Yu, Chaehyun,Omura, Yuji 
TITLE  Top forwardbackward asymmetry and the CDF Wjj excess in leptophobic U(1) flavor models 
ARCHIVE  arXiv:1108.0350 
FILE  
JOURNAL  PHYSICAL REVIEW D, 2012 
ABSTRACT  We construct anomalyfree leptophobic U(1) flavor models with light Z (similar to 145 GeV). In order to allow renormalizable Yukawa interactions for the standard model chiral fermions, new Higgs doublets with nonzero U(1) charges are introduced. Then the neutral (pseudo) scalar Higgs bosons as well as Z contribute to the t (t) over bar and the same sign top pair productions [sigma(t (t) over bar) and sigma(tt)], and one can evade the strong constraint from sigma(tt). The top forwardbackward asymmetry (A(FB)) and Wjj excess at CDF could be accommodated by A(FB)(New) = 0.084 similar to 0.12 and sigma(Wjj) less than or similar to O(10) pb X sin(2)2 beta. 

Publication at kias
NUMBER  P11016 
AUTHOR  Ko, P.,Yu, Chaehyun,Omura, Yuji 
TITLE  Dijet resonance from leptophobic Z and light baryonic cold dark matter 
ARCHIVE  1104.4066 
FILE  
JOURNAL  PHYSICS LETTERS B, 2012 
ABSTRACT  In light of the recent CDF report on the excess in the Wjj channel, we analyze (non)supersymmetric U(1)(B) x U(1)(l) model, interpreting the dijet peak as a leptophobic U(1)(B) gauge boson. If this excess is confirmed, it has an interesting implication for the baryonic cold dark matter (CDM) in the model: there should be light CDM with a few GeV mass, and direct detection cross section at the level of a few x 10(2) pb. (C) 2012 Elsevier B.V. All rights reserved. 

Publication at kias
NUMBER  P11025 
AUTHOR  Ko, P.,Omura, Y. 
TITLE  Light dark matter in leptophobic Z models 
ARCHIVE  arXiv:1106.0885 
FILE  
JOURNAL  PHYSICAL REVIEW D, 2012 
ABSTRACT  Recent experimental results in direct dark matter detection may be interpreted in terms of a dark matter particle of mass around 10 GeV/c(2). We show that the required scenario can be realized with a new dark matter particle charged under an extra Abelian gauge boson Z that couples to quarks but not leptons. This is possible provided the Z gauge boson is very light, around 1020 GeV/c(2) in mass, and the gauge coupling constant is small, alpha similar to 10(5). Such scenarios are not constrained by accelerator data. 

Publication at kias
NUMBER  P11043 
AUTHOR  Ko, P. 
TITLE  Mass dependent top forwardbackward asymmetry in the effective Lagrangian approach: Addendum to Model independent analysis of the forwardbackward asymmetry of top quark production at the Tevatron 
ARCHIVE  1111.3180 [hepph] 
FILE  
JOURNAL  PHYSICS LETTERS B, 2012 
ABSTRACT  Recently the CDF and the D0 Collaborations presented the data on the top forwardbackward (FB) asymmetry A(FB) as functions of Mt((t)) over bar and Delta y equivalent to y(t)  y ((t)) over bar. We study these observables in the effective Lagrangian approach with dimension6 qqtt contact interactions, and compare with the CDF and DO data. When we stay within the validity region of the effective Lagrangian approach, the mass dependent top FB asymmetry turns out to be smaller than the CDF data, more than 2sigma away. If this discrepancy remains in the future data with better statistics, it would imply that the effective Lagrangian approach is not adequate for the top FB asymmetry, and a new physics scale around a few hundred GeV in the t or uchannel may be responsible for the observed top FB asymmetry. (C) 2012 Elsevier B.V. All rights reserved. 

Publication at kias
NUMBER  P11064 
AUTHOR  Ko, P.,Baek, Seungwon,Park, WanIl 
TITLE  Search for the Higgs portal to a singlet fermionic dark matter at the LHC 
ARCHIVE  arXiv:1112.1847 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2012 
ABSTRACT  We consider a simple extension of the standard model with a singlet fermionic dark matter. Its thermal relic density can be easily accommodated by a real Singlet scalar messenger that mixes with the standard model Higgs boson. The model can change significantly the Higgs signals at the LTIC via sizable invisible decays of two Higgslike scalar bosons. After imposing the constraints from the electroweak precision tests, colliders and dark matter search experiments, one concludes that two or one or none of the two Higgs bosons, depending on the mass relations among two scalar bosons and the dark matter fermion and their couplings. In particular, if a standard model Higgslike scalar boson is discovered around 120125 GeV region at the LHC, it would be almost impossible to find the second Higgslike boson since it is mostly a singlet scalar, whether it is heavier or lighter. This model can be further tested by direct dark matter search experiments. 

Publication at kias
NUMBER  P11045 
AUTHOR  Ko, P.,Yu, Chaehyun,Omura, Yuji 
TITLE  Chiral U(1) flavor models and flavored Higgs doublets: the top FB asymmetry and the Wjj 
ARCHIVE  1008.4005 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2012 
ABSTRACT  We present U(1) flavor models for leptophobic Z with flavor dependent couplings to the righthanded uptype quarks in the Standard Model (SM), which can accommodate the recent data on the top forwardbackward (FB) asymmetry and the dijet resonance associated with a W boson reported by CDF Collaboration. Such flavordependent leptophobic charge assignments generally require extra chiral fermions for anomaly cancellation. Also the chiral nature of U(1) flavor symmetry calls for new U(1)charged Higgs doublets in order for the SM fermions to have realistic renormalizable Yukawa couplings. The stringent constraints from the top FB asymmetry at the Tevatron and the same sign top pair production at the LHC can be evaded due to contributions of the extra Higgs doublets. We also show that the extension could realize cold dark matter candidates. 

Publication at kias
NUMBER  P11017 
AUTHOR  Ko, P. 
TITLE  Possible common origin of the top forwardbackward asymmetry and the CDF Wjj excess 
ARCHIVE  arXiv:1104.4443 
FILE  
JOURNAL  PHYSICAL REVIEW D, 2011 
ABSTRACT  A colorsinglet neutral vector boson is considered as a possible common origin of the top forwardbackward asymmetry and the CDF dijet resonance. We identify chiral and flavor structures of the couplings of this new vector boson to the standard model quarks for which one could accommodate both data. We also demonstrate that nonvanishing observables involving longitudinal top polarizations can provide useful criteria for the possible existence of parity violating new physics in the q (q) over bar > t (t) over bar process, and discrimination between the flavorconserving and flavorviolating cases. 

Publication at kias
NUMBER  P10043 
AUTHOR  Ko, P.,Omura, Y. 
TITLE  Supersymmetric U(1)(B) x U(1)(L) model with leptophilic and leptophobic cold dark matters 
ARCHIVE  1012.4679 
FILE  
JOURNAL  PHYSICS LETTERS B, 2011 
ABSTRACT  We consider a supersymmetric model with extra U(1)(B) x U(1)(L) gauge symmetry that is broken spontaneously. Salient features of this model are that there are three different types of cold dark matter (CDM) candidates, and neutral scalar sector has a rich structure. Light CDM with sigma(Sl) similar to 10(3+/1) pb can be easily accommodated by leptophobic dark matter (chi(B)) with correct relic density, if the U(1)(B) gauge boson mass is around 2m(chi B). Also the PAMELA and Fermi/EAT data can be fit by leptophilic CDM with mass similar to 1 TeV. There could be interesting signatures of new fermions and new gauge bosons at the LHC. (C) 2011 Elsevier B.V. All rights reserved. 

Publication at kias
NUMBER  P10038 
AUTHOR  Ko, P. 
TITLE  Longitudinal top polarization as a probe of a possible origin of forwardbackward asymmetry of the top quark at the Tevatron 
ARCHIVE  1011.5976 
FILE  
JOURNAL  PHYSICS LETTERS B, 2011 
ABSTRACT  If the forwardbackward (FB) asymmetry of top quark (A(FB)) observed at the Tevatron deviates from the SM prediction, there must be Pviolating interactions in q (q) over bar > t (t) over bar. This new interaction will necessarily affect the top spin polarization. In this Letter, we perform a model independent analysis on the longitudinal (anti)top polarization (PL and (P) over bar (L)) using an effective lagrangian with dim6 fourquark operators relevant for q (q) over bar > t (t) over bar, and show that the Podd observable corresponding to the polarization difference (PL  (P) over bar (L)) gives important informations on the chiral structures of new physics that might be relevant to the A(FB). (C) 2011 Elsevier B.V. All rights reserved. 

Publication at kias
NUMBER  P11010 
AUTHOR  Ko, P. 
TITLE  Scale Invariant Extension of the Standard Model with a Strongly Interacting Hidden Sector 
ARCHIVE  arXiv:1103.2571 
FILE  
JOURNAL  PHYSICAL REVIEW LETTERS, 2011 
ABSTRACT  We present a scale invariant extension of the standard model with a new QCDlike strong interaction in the hidden sector. A scale Lambda(H) is dynamically generated in the hidden sector by dimensional transmutation, and chiral symmetry breaking occurs in the hidden sector. This scale is transmitted to the SM sector by a real singlet scalar messenger S and can trigger electroweak symmetry breaking. Thus all the mass scales in this model arise from the hidden sector scale Lambda(H), which has quantum mechanical origin. Furthermore, the lightest hadrons in the hidden sector are stable by the flavor conservation of the hidden sector strong interaction, and could be the cold dark matter (CDM). We study collider phenomenology, relic density, and direct detection rates of the CDM of this model. 

Publication at kias
NUMBER  P10017 
AUTHOR  Ko, P.,Yu, Chaehyun 
TITLE  pp > J/psi plus Gamma plus X as a clean probe to the quarkonium production mechanism 
ARCHIVE  1006.3846 
FILE  
JOURNAL  PHYSICAL REVIEW D, 2011 
ABSTRACT  We report that, unlike most inclusive quarkoniumproduction processes, the production rate for pp > J/psi + Gamma + X dominantly depends on two not wellknown longdistance nonrelativistic QCD matrix elements, < O8(J/psi)(S3(1))> and < O8(Gamma)(S3(1))> at leading order in the strong coupling constant, which account for the transition probabilities of the coloroctet spintriplet heavyquarkantiquark pairs c (c) over bar (8)(S3(1)) > J/psi and b (b) over bar (8)(S3(1)) > Gamma, respectively. With the integrated luminosity similar to 100 fb(1) at the centerofmomentum energy root s = 14 TeV we expect that approximately 1900 pp > J/psi + Gamma + X events can be observed at the CERN Large Hadron Collider by tagging muon pairs, which are enough to probe to the coloroctet mechanism. The forthcoming measurement may provide a useful constraint to resolve the decadeold puzzle for the polarization of prompt J/psi at the Fermilab Tevatron. If corresponding measured rate is significantly less than the prediction, it may imply that the current values for the coloroctet matrix elements are overestimated. 

Publication at kias
NUMBER  P07050 
AUTHOR  Ko, P. 
TITLE  Electroweak symmetry breaking and cold dark matter from strongly interacting hidden sector 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B, 2011 
ABSTRACT  We consider a hidden sector with a vectorlike confining gauge theory like QCD with N(h,c) colors and N(h,f) light quarks Q(h) in the hidden sector. Then a scale Lambda(H) would be generated by dimensional transmutation, and chiral symmetry breaking occurs in the hidden sector. This scale Lambda(H) can play a role of the SM Higgs mass parameter, triggering electroweak symmetry breaking (EWSB). Furthermore the lightest mesons in the hidden sector is stable by flavor conservation of the hidden sector strong interaction, and could be a good cold dark matter (CDM). We study collider phenomenology, and relic density and direct detection rates of the CDM of this model. (C) 2010 Elsevier B.V. All rights reserved. 

Publication at kias
NUMBER  P10023 
AUTHOR  Ko, P.,Yu, Chaehyun 
TITLE  Inclusive doublequarkonium production at the Large Hadron Collider 
ARCHIVE  1007.3095 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2011 
ABSTRACT  Based on the nonrelativistic QCD (NRQCD) factorization formalism, we investigate inclusive productions of two spintriplet Swave quarkonia pp > 2J/psi + X, 2 gamma + X, and J/psi + gamma + X at the CERN Large Hadron Collider. The total production rates integrated over the rapidity (y) and transversemomentum (pT) ranges vertical bar y vertical bar < 2.4 and pT < 50GeV are predicted to be sigma[pp > 2J/psi + X] = 22 (35) nb, sigma[pp > 2 gamma + X] = 24 (49) pb, and sigma[pp > J/psi + gamma + X] = 7 (13) pb at the centerofmomentum energy root s = 7 (14) TeV. In order to provide predictions that can be useful in both small and largepT regions, we do not employ the fragmentation approximation and we include the spintriplet Swave colorsinglet and coloroctet channels for each quarkonium final state at leading order in the strong coupling. The pT distributions of pp > 2J/psi + X and 2 gamma + X in the lowpT region are dominated by the colorsinglet contributions. At leading order in the strong coupling, the colorsinglet channel is absent for pp > J/psi + gamma + X. Therefore, the process pp > J/psi + gamma + X may provide a useful probe to the coloroctet mechanism of NRQCD. 

Publication at kias
NUMBER  P10021 
AUTHOR  Ko, P. 
TITLE  Addendum to: Implications of the measurements of BS(B)overbar(S) mixing on SUSY models 
ARCHIVE  arXiv:1006.5821 
FILE  
JOURNAL  PHYSICAL REVIEW D, 2010 
ABSTRACT  This is an addendum to the previous publication, [P. Ko and J.h. Park, Phys. Rev. D 80, 035019 (2009).]. The semileptonic charge asymmetry in BS decays is discussed in the context of the general minimal supersymmetric standard model with gluinomediated flavor and CP violation in light of the recent measurements at the Tevatron. 

Publication at kias
NUMBER  P10020 
AUTHOR  Ko, P. 
TITLE  Model independent analysis of the forwardbackward asymmetry of top quark production at the Tevatron 
ARCHIVE  arXiv:0912.1105 
FILE  
JOURNAL  PHYSICS LETTERS B, 2010 
ABSTRACT  Motivated by a possible anomaly in the forwardbackward (FB) asymmetry of top quark (A(FB)) observed at the Tevatron, we perform a model independent analysis on q (q) over bar > t (t) over bar using an effective Lagrangian with dim6 fourquark operators. We derive necessary conditions on new physics structures and the couplings that are consistent with the t (t) over bar production cross section and AFB measured at the Tevatron, and discuss possible new physics scenarios that could generate such dim6 operators. (C) 2010 Elsevier B.V. All rights reserved. 

Publication at kias
NUMBER  
AUTHOR  Ko, Pyungwon 
TITLE  Phenomenology of U(1)(L muL tau) charged dark matter at PAMELA/FERMI and colliders 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, 2009 
ABSTRACT  Recent data on e(+)/e() and (p) over bar cosmic rays suggest that dark matter annihilate into the standard model (SM) particles through new leptophilic interaction. In this paper, we consider a standard model extension with the gauged U(1)(L muL tau) group, with a new Dirac fermion charged under this U(1) as a dark matter. We study the muon (g2)(mu), thermal relic density of the cold dark matter, and the collider signatures of this model. Z productions at the Tevatron or the LHC could be easily order of O(1)O(10(3))fb. 

Publication at kias
NUMBER  P09040 
AUTHOR  Ko, Pyungwon 
TITLE  Stable Higgs bosons as cold dark matter 
ARCHIVE  0908.0212 
FILE  
JOURNAL  PHYSICS LETTERS B, 2009 
ABSTRACT  In a class of the gaugeHiggs unification models the 4D neutral Higgs boson, which is a part of the extradimensional component of the gauge fields, becomes absolutely stable as a consequence of the gauge invariance and dynamically generated new parity, serving as a promising candidate for cold dark matter (CDM). We show that the observed relic abundance of cold dark matter is obtained in the SO(5) x U(l) model in the warped space with the Higgs mass around 70 GeV. The Higgsnucleon scattering cross section is found to be close to the current CDMS II and XENON10 bounds in the direct detection of dark matter. (C) 2009 Elsevier B.V. All rights reserved. 

Publication at kias
NUMBER  
AUTHOR  Ko, P. 
TITLE  Implications of the measurements of Bs(B)overbars mixing on supersymmetric models 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D, 2009 
ABSTRACT  We derive constraints on the mass insertion parameters from the recent measurements of Bs(B) over bar (s) mixing, and discuss their implications on SUSY breaking mediation mechanisms and SUSY flavor models. Some SUSY flavor models are already excluded or disfavored by Bs(B) over bar (s) mixing. We also discuss how to test the SM and SUSY models in the future experiments, by studying other CP violating observables related to b > s transition, such as the timedependent CP asymmetry in Bd > phi KS and the direct CP asymmetry in B > Xs gamma. 

Publication at kias
NUMBER  P07051 
AUTHOR  Ko, Pyungwon 
TITLE  Sflavor mixing map viewed from a high scale in supersymmetric SU(5) 
ARCHIVE  0809.2784 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2008 
ABSTRACT  We study flavor violation in a supersymmetric SU(5) grand unification scenario in a modelindependent way employing mass insertions. We examine how the quark and the lepton sector observables restrict sfermion mixings. With a low soft scalar mass, a lepton flavor violating process provides a stringent constraint on the flavor structure of righthanded downtype squarks. In particular, mu > e gamma turns out to be highly susceptible to the 13 and 23 mixings thereof, due to the radiative correction from the top Yukawa coupling to the scalar mass terms of 10. With a higher scalar mass around the optimal value, in contrast, the quark sector inputs such as Bmeson mixings and hadron electric dipole moment, essentially determine the room for sfermion mixing. We also discuss the recent deviation observed in Bs mixing phase, projected sensitivity of forthcoming experiments, and ways to maintain the power of leptonic restrictions even after incorporating a solution to fix the incorrect quarklepton mass relations. 

Publication at kias
NUMBER  P08012 
AUTHOR  Ko, P. 
TITLE  Neutral scalar Higgs bosons in the USSM at the LHC 
ARCHIVE  0801.2361 
FILE  
JOURNAL  JOURNAL OF PHYSICS GNUCLEAR AND PARTICLE PHYSICS, 2008 
ABSTRACT  We study the possibility of discovering neutral scalar Higgs bosons in the U(1)extended supersymmetric standard model (USSM) at the CERN Large Hadron Collider (LHC), by examining their productions via the exoticquark loop in the gluonfusion process at leading order. It is possible in some parameter region that the neutral scalar Higgs bosons may have stronger couplings with the exotic quarks than with top quarks. In this case, the exotic quarks may contribute more actively than top quarks in production of the neutral scalar Higgs bosons in the gluonfusion process. We find that there is indeed some parameter region in the USSM that support our speculations. 

Publication at kias
NUMBER  
AUTHOR  Ko, Pyungwon 
TITLE  Electroweak symmetry breaking and cold dark matter from hidden sector technicolors 
ARCHIVE  
FILE  
JOURNAL  INTERNATIONAL JOURNAL OF MODERN PHYSICS A, 2008 
ABSTRACT  We consider models with a vectorlike confining gauge theory in the hidden sector, and demonstrate that the origin of the electroweak symmetry breaking (EWSB) is due to the dimensional transmutation in the hidden sector gauge theory, and the lightest mesons in the hidden sector could be a good cold dark matter (CDM) candidate. There would be more than one neutral Higgslike scalar bosons, and they could decay mainly into the CDM pair, if that decay channel is kinemtically allowed. 

Publication at kias
NUMBER  P08071 
AUTHOR  Kim, Youngman,Wu, XiaoHong,Ko, P. 
TITLE  Holographic QCD beyond the leading order 
ARCHIVE  0804.2710 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2008 
ABSTRACT  We consider a holographic QCD model for light mesons beyond the leading order in the context of 5dim gauged linear sigma model on the interval in the AdS(5) space. We include two dimension6 operators in addition to the canonical bulk kinetic terms, and study chiral dynamics of pi, rho, a(1) and some of their KK modes. As novel features of dim6 operators, we get nonvanishing Br(a(1) > pi gamma), the electromagnetic form factor and the charge radius of a charged pion, which improve the leading order results significantly and agree well with the experimental results. 

Publication at kias
NUMBER  P08011 
AUTHOR  Ko, Pyungwon 
TITLE  Probing nonstandard neutrino physics by two identical detectors with different baselines 
ARCHIVE  arXiv:0712.4314 
FILE  
JOURNAL  PHYSICAL REVIEW D, 2008 
ABSTRACT  The KamiokaKorea twodetector system is a powerful experimental setup for resolving neutrino parameter degeneracies and probing CP violation in neutrino oscillation. In this paper, we study sensitivities of the same setup to several nonstandard neutrino physics such as quantum decoherence, tiny violation of Lorentz symmetry, and nonstandard interactions of neutrinos with matter. We show that it can achieve significant improvement on the current bounds on nonstandard neutrino physics. In most cases, the KamiokaKorea twodetector setup is more sensitive than the onedetector setup, either in Kamioka or in Korea, except for the cases when Lorentz symmetry is broken in a CPTviolating manner and the nonstandard neutrino interactions with matter is present. 

Publication at kias
NUMBER  
AUTHOR  Ko, P. 
TITLE  MSSM Higgs sector CP violation at photon colliders: revisited 
ARCHIVE  
FILE  
JOURNAL  EUROPEAN PHYSICAL JOURNAL C, 2008 
ABSTRACT  The CP violating phases in soft SUSY breaking terms may induce indirect CP violation in the neutral Higgs boson sector through SUSY particle loops as well as direct CP violation in the gamma gamma > Hi (i=1,2,3) through CP violating vertices. We present a complete analysis of the MSSM Higgs sector CP violation at photon colliders including the chargino loop contributions in the regime tan beta less than or similar to 20, where the CP violating mixing in the neutral Higgs sector is very strongly influenced by the scalar top loop, more so than the chargino and neutralino ones. However, the CP violating phases of the higgsino and wino mass parameters may still generate direct CP violation in gamma gamma > Hi. In this process, the CP violating phenomena become very rich, and thus we study the production rates and polarization asymmetries in the Higgs production in detail. Photon colliders with high luminosity and well controlled polarized initial photon beams are indispensable in determining the CP properties of neutral Higgs bosons. 

Publication at kias
NUMBER  P07047 
AUTHOR  Ko, P.,Wu, XiaoHong 
TITLE  Antisymmetric rank2 tensor unparticle physics 
ARCHIVE  arXiv:0709.0629 
FILE  
JOURNAL  PHYSICAL REVIEW D, 2007 
ABSTRACT  We present the phenomenology of antisymmetric rank2 tensor unparticle operator OU,A(mu nu) with scaling dimension dU. We consider the physical effects of operator OU,A(mu nu) in Z(0) boson invisible decays Z(0)> U, Z(0)> b (b) over bar channel, the electroweak precision observable S parameter, and the muon anomalous magnetic dipole moment. The Z(0) boson invisible decay gives a very stringent constraint in the (Lambda U,MU) plane, and only small r equivalent to Lambda U/MU less than or similar to 0.1 is favored, when Lambda U is order of several 100 GeV. When the phenomenological parameter mu, which parameterizes the scale invariance breaking, goes to 0, the S parameter and the muon (g2) diverge for 1 < dU < 2, while for nonzero mu, there will be constraints on (Lambda U,MU) which are more stringent than those obtained from collider experiments. 

Publication at kias
NUMBER  P07015 
AUTHOR  Ko, Pyungwon 
TITLE  Stringderived D4 flavor symmetry and phenomenological implications 
ARCHIVE  0704.2807 
FILE  
JOURNAL  PHYSICAL REVIEW D, 2007 
ABSTRACT  In this paper we show how some flavor symmetries may be derived from the heterotic string, when compactified on a 6D orbifold. In the body of the paper we focus on the D4 family symmetry, recently obtained in Z(3)xZ(2) orbifold constructions. We show how this flavor symmetry constrains fermion masses, as well as the soft SUSY breaking mass terms. Flavor symmetry breaking can generate the hierarchy of fermion masses and at the same time the flavor symmetry suppresses large flavor changing neutral current processes. 

Publication at kias
NUMBER  P05065 
AUTHOR  Ko, P 
TITLE  MSSM anatomy of the polarization puzzle in B >phi K* decays 
ARCHIVE  hepph/0511129 
FILE  
JOURNAL  PHYSICAL REVIEW D, 2006 
ABSTRACT  We analyze the B >phi K* polarization puzzle in the minimal supersymmetric standard model (MSSM) including the neutral Higgs boson (NHB) contributions. To calculate the nonfactorizable contributions to the hadronic matrix elements of operators, we have used the QCD factorization framework to the alpha(s) order. It is shown that the recent experimental results of the polarization fractions in B >phi K* decays, which are difficult to be explained in SM, could be explained in MSSM if there are flavor nondiagonal squark mass matrix elements of 2nd and 3rd generations, which also satisfy all relevant constraints from known experiments (B > Xs gamma,Bs >mu(+)mu(),B > Xs mu(+)mu(),B > X(s)g,Delta Ms, etc.). We have shown in detail that the experimental results can be accommodated with the flavor nondiagonal mass insertion of chirality RL, RL+LR, RR, or LL+RR when the NHB contributions as well as O(alpha(s)) corrections of hadronic matrix elements of operators are included. However, the branching ratios for the decay are smaller than the experimental measurements. 

Publication at kias
NUMBER  P05029 
AUTHOR  Ko, PW 
TITLE  Bs >mu(+)mu() and the upwardgoing muon flux from the WIMP annihilation in the sun or the earth 
ARCHIVE  hepph/0506115 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2005 
ABSTRACT  We consider the upwardgoing muon flux due to the WIMP annihilations in the cores of the sun and the earth, including the upper bound on the branching ratio for Bs > mu(+)mu() decay. We find that the constraint from Bs > mu(+)mu() is very strong in most parameter space, and exclude the supergravity parameter space regions where the expected upwardgoing muon fluxes are within the expected reach of IceCube. 

Publication at kias
NUMBER  P05019 
AUTHOR  Ko, P,Park, JH 
TITLE  Re(epsilon /epsilon(K)) versus Bd >phi KS CP asymmetry 
ARCHIVE  hepph/0503102 
FILE  
JOURNAL  PHYSICAL REVIEW D, 2005 
ABSTRACT  In a SUSY GUT seesaw scenario, the largeness of the atmospheric neutrino mixing can reflect itself into an enhanced flavor changing mixing of beauty and strange righthanded scalar quarks. If the CP violating phase in such downtype squark RR insertion is the main source of CP asymmetry in Bd>phi KS and the gluino contributions to K0(K) over bar (0) and B0(B) over bar (0) mixing are negligible, there is a correlation between Re (epsilon()/epsilon(K)) and Bd>phi KS CP asymmetry, in addition to that with the strange quark CEDM. The current data on Re (epsilon()/epsilon(K))=(16.7 +/ 2.6)x10(4) imply that Sphi K should be greater than similar to 0.5(0.25) for mu tan beta=1(5) TeV, assuming the RR dominance in b > s transition and the minimal supergravity type boundary conditions for soft parameters. 

Publication at kias
NUMBER  P05030 
AUTHOR  Ko, P 
TITLE  Direct detection of neutralino dark matter in supergravity 
ARCHIVE  hepph/0505019 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2005 
ABSTRACT  The direct detection of neutralino dark matter is analysed in general supergravity scenarios, where nonuniversal soft scalar and gaugino masses can be present. In particular, the theoretical predictions for the neutralinonucleon cross section are studied and compared with the sensitivity of dark matter detectors. We take into account the most recent astrophysical and experimental constraints on the parameter space, including the current limit on B(Bs(0) > mu(+)mu()). The latter puts severe limitations on the dark matter scattering cross section, ruling out most of the regions that would be within the reach of present experiments. We show how this constraint can be softened with the help of appropriate choices of nonuniversal parameters which increase the Higgsino composition of the lightest neutralino and minimise the chargino contribution to the b > s transition. 

Publication at kias
NUMBER  P05020 
AUTHOR  Ko, P,Park, JH 
TITLE  Lepton masses and mixing angles from heterotic orbifold models 
ARCHIVE  hepph/0503029 
FILE  
JOURNAL  PHYSICAL REVIEW D, 2005 
ABSTRACT  We systematically study the possibility for realizing realistic values of lepton mass ratios and mixing angles by using only renormalizable Yukawa couplings derived from the heterotic Z(6)I orbifold. We assume one pair of up and down sector Higgs fields. We consider both the Dirac neutrino mass scenario and the seesaw scenario with degenerate righthanded majorana neutrino masses. It is found that realistic values of the charged lepton mass ratios, m(e)/m(tau) and m(mu)/m(tau), the neutrino mass squared difference ratio, Delta m(31)(2)/Delta m(21)(2), and the lepton mixing angles can be obtained in certain cases. 

Publication at kias
NUMBER  
AUTHOR  Ko, P 
TITLE  Colorevaporationmodel calculation of e plus e J/y plus cc plus X at s=10. 6 GeV 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D, 2005 
ABSTRACT  Measurements by Belle Collaboration of the cross section for inclusive J/y production in e(c)(+e annihilation have been a serious challenge to current heavyquarkonium theory. In particular, the measured cross sections for exclusive J/y+h) and inclusive J/y+c (c) over bar +X differ from nonrelativistic QCD predictions by an order of magnitude. In order to check if other available alternative theories can resolve such a large discrepancy, we calculate the cross section for inclusive J/y+c (c) over bar +X based on the colorevaporation model. As a phenomenological model, the colorevaporation model is still employed to predict cross sections for inclusive quarkonium production in various processes. Our results show that the colorevaporationmodel prediction is even smaller than the nonrelativistic QCD prediction by an order of magnitude. The resultant colorevaporationmodel prediction for the J/y+c (c) over bar +X fraction in the inclusive J/y production cross section is 0.049, while the empirical value measured by Belle Collaboration is 0.82. 

Publication at kias
NUMBER  P17139 
AUTHOR  Baek, S,Kim, YG,Ko, P 
TITLE  Neutralino dark matter scattering and Bs >mu(+)mu() in SUSY models 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2005 
ABSTRACT  It is pointed out that there is a strong correlation between the neutralino dark matter scattering cross section sigma((chi) over tildep) and the branching ratio for Bs > mu(+)mu() within minimal supergravity (mSUGRA) and its extensions. This correlation arises mainly from tan beta and heavy neutral Higgs mass dependence, and shows a nice interplay between vastly different two observables within supersymmetric models. Current upper limit on B(Bs > mu(+)mu()) < 5.8 x 10(7) excludes substantial parameter space where sigma(<(chi)over tilde>p) is within the CDMS sensitivity region. 

Publication at kias
NUMBER  P02065 
AUTHOR  Ko, P,Baek, S 
TITLE  SUSY breaking mediation mechanisms and (g2)mu, B > Xs gamma, B > X(s)l(+)l() and Bs > mu(+)mu() 
ARCHIVE  hepph/0208112 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 2003 
ABSTRACT  We show that there are qualitative differences in correlations among (g  2)(mu), B > Xs gamma, B > X(s)l(+)l() and Bs > mu(+)mu() in various SUSY breaking mediation mechanisms: minimal supergravity (mSUGRA), gauge mediation (GMSB), anomaly mediation (AMSB), gaugino mediation ((g) over tilde MSB), weakly and strongly interacting string theories, and D brane models. After imposing the direct search limits on the Higgs boson and SUSY particle search limits and B > X(s)gamma branching ratio, we find all the scenarios can accommodate the a(mu) = (g  2)(mu)/2 in the range of (a few tens) x 10(10), and predict that the branching ratio for B > X(s)l(+)l() can differ from the standard model (SM) prediction by +/20% but no more. On the other hand, the Bs > mu(+)mu() is sensitive to the SUSY breaking mediation mechanisms through the pseudoscalar and stop masses (m(A) and m((t) over tilde1)), and the stop mixing angle. In the GMSB with a small messenger number, the AMSB, the (g) over tilde MSB and the noscale scenarios, one finds that B(Bs > mu(+)mu()) less than or similar to 2 x 10(8), which is below the search limit at the Tevatron Run II. Only the mSUGRA or string inspired models can generate a large branching ratio for this decay. 

Publication at kias
NUMBER  
AUTHOR  Baek, S,Ko, P 
TITLE  Implications on supersymmetrybreaking mediation mechanisms from observing Bs >mu(+)mu() and the muon g2 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW LETTERS, 2002 
ABSTRACT  We consider Bs>mu(+)mu() and the muon (g2)(mu) in various supersymmetrybreaking mediation mechanisms. If the decay Bs>mu(+)mu() is observed at Tevatron Run II with a branching ratio larger than similar to2x10(8), the noscale supergravity (including the gaugino mediation), the gauge mediation scenario with a small number of messenger fields and low messenger scale, and a class of anomaly mediation scenarios will be excluded, even if they can accommodate a large muon (g2)(mu). On the other hand, the minimal supergravity scenario and similar mechanisms derived from string models can accommodate this observation. 

Publication at kias
NUMBER  P02007 
AUTHOR  Baek, S,Ko, P 
TITLE  Muon anomalous magnetic moment from effective supersymmetry 
ARCHIVE  hepph/0203251 
FILE  
JOURNAL  EUROPEAN PHYSICAL JOURNAL C, 2002 
ABSTRACT  We present a detailed analysis on the possible maximal value of the union (g  2)(mu) equivalent to 2alpha(mu) within the context of effective SUSY models with R parity conservation. First of all, mixing among the second susy and the third family sleptons can contribute at one loop level to alpha(mu)(SUSY) and r > mugamma simultaneously. One finds that alpha(mu)(SUSY) can be as large as (1020) x 10(10) for any tan beta, imposing an upper limit on the r > mugamma susy branching ratio. Furthermore, the two loop BarrZee type contributions to alpha(mu)(SUSY) may be significant for large tan,3, if a stop is light and p and At are large enough ( 0 (1) TeV). In this case, it is possible to have alpha(mu)(SUSY) up to O(10) x 10(10) without conflicting with r > lgamma. We conclude that the possible maximal value for alpha(mu)(SUSY) is about similar to20 x 10(10) for any tan beta. Therefore the BNL experiment on the muon alpha(mu) can exclude the effective SUSY models only if the measured deviation is larger than similar to 30 x 10(10). 

Publication at kias
NUMBER  P98021 
AUTHOR  Ko, P 
TITLE  Possible newphysics signals in b > s gamma and b > sl(+)l() 
ARCHIVE  hepph/9810336 
FILE  
JOURNAL  NUCLEAR PHYSICS B, 1999 
ABSTRACT  We consider possible newphysics contributions to b > sl(+)l() assuming that newphysics modifies (chromo)magnetic and electric form factors in b > s gamma* and b > sg with the same chirality structure as in the standard model. Parametrizing the newphysics effects on b >, s gamma* and b > sg in terms of four real parameters, one finds that there is a large enough region of parameter space in which the measured branching ratio for B > X(s)gamma can be accommodated, and the predicted CP violation effect could be as large as similar to 30%. Moreover, the branching ratio and the forwardbackward asymmetry of a lepton in B > X(s)l(+)l() and the tau polarization asymmetry in B > X(s)tau(+)tau() can deviate from the SM predictions by a factor of similar to 2, which can be accessible at Bfactories. We also discuss these observables in a specific class of supersymmetric models with gluinomediated flavor changing neutral currents (FCNC). (C) 1999 Elsevier Science B.V. 

Publication at kias
NUMBER  P98027 
AUTHOR  Ko, P 
TITLE  Mass matrix ansatz for degenerate neutrinos consistent with solar and atmospheric neutrino data 
ARCHIVE  hepph/9706535 
FILE  
JOURNAL  PHYSICS LETTERS B, 1998 
ABSTRACT  We suggest mass matrices for neutrinos and charged leptons that can explain solar and atmospheric neutrino data. The resulting flavor mixing matrix Vnu has a property that (Vnu)(13) = 0, thus making nu(e) <> nu(mu) and nu(mu) <> nu(tau) oscillations to be effectively a twochannel problem. Phenomenological consequences of the lepton mass matrix ansatze are consistent with the current data on various type of neutrino oscillation experiments except the LSND measurement. Three neutrinos, being almost degenerate with Sigmam(nu i) less than or similar to 1 eV, can be a part of hot dark matter without any conflict with the constraint from neutrinoless double beta decay experiments. The nu(mu) <> nu(tau) oscillation, sin(2)2 theta(mu tau), is predicted to be 0.860.97 with Delta m(mu tau)(2) similar or equal to 2 X 10(3) eV(2), which is consistent with the atmospheric neutrino data and can be tested further at the planned MINOS and K2K experiments searching for nu(mu) > nu(tau) oscillation. (C) 1998 Elsevier Science B.V. All rights reserved. 


Publication(career)
NUMBER  
AUTHOR  Choi, SooMin; Lee, Hyun Min; Ko, Pyungwon; Natale, Alexander 
TITLE  Resolving phenomenological problems with stronglyinteractingmassiveparticle models with dark vector resonances 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D, 98(1), 15034, 2018 
ABSTRACT  We consider a light dark matter candidate that is produced by the freezeout mechanism with 3 > 2 annihilations, the socalled strongly interacting massive particles (SIMPs). SIMPs are identified as dark pions in dark chiral perturbation theory (ChPT) in which both light mass and strong coupling needed for SIMPs can be realized by strong dynamics. In QCDlike theories with SU(3)(L) x SU(3)(R)/SU(3)(V) flavor symmetry, including dark vector mesons in the hidden local symmetry scheme, we illustrate that dark vector mesons unitarize the dark ChPT efficiently, thus determining the correct relic density condition within the validity of the dark ChPT.


Publication(career)
NUMBER  
AUTHOR  Dutta, Bhaskar; Kamon, Teruki; Ko, P.; Li, Jinmian 
TITLE  Prospects for discovery and spin discrimination of dark matter in Higgs portal DM models and their extensions at 100 TeV pp collider 
ARCHIVE  
FILE  
JOURNAL  EUROPEAN PHYSICAL JOURNAL C, 78(7), 595, 2018 
ABSTRACT  We study the discovery and discriminating prospects of the Higgs portal dark matter (DM) models for scalar, fermion and vector DM and their extensions in protonproton (pp) collisions. The t (t) over bar +DM associated production in dileptonic final states is considered, in which the stransverse mass of two leptons is found to be effective in suppressing the Standard Model backgrounds along with the missing transverse energy and the angle between two leptons. The distributions of missing transverse energy and polar angle between two leptons are used for a discrimination of the spin nature of DM. For the proposed benchmark points, the discovery/exclusion can be made with an integrated luminosity less than 1 ab(1) given a 1% systematic uncertainty, while the spin discrimination require integrated luminosity of a few O(10) ab(1) given a 0.5% systematic uncertainty. The DM phenomenology is also discussed. A consistent DM candidate can be obtained either by extending our model where the Higgs portal couples to excited dark states that decay into DM, or modifying the coupling form into pseudoscalar.


Publication(career)
NUMBER  
AUTHOR  Ko, Pyungwon 
TITLE  Particle, Astroparticle Physics and Cosmology in Dark Matter Models with Dark Gauge Symmetries 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF THE KOREAN PHYSICAL SOCIETY, 73(4), 449465, 2018 
ABSTRACT  In this review, I describe a class of dark matter (DM) models where DM is either stable due to unbroken dark gauge symmetries, or longlived due to accidental global symmetries resulting from the underlying dark gauge symmetries. Within these models, I discuss various topics on DM in the context of particle and astroparticle physics and cosmology: DM thermal relic density and (in)direct detection, Higgs inflation assisted with Higgs portal interaction, dark radiation (DR), DMDR interaction and suppression of the matter power spectrum at large k, strong first order phase transition and gravitational wave production, etc.. Especially I emphasize the importance of dark gauge symmetries, unitarity and renormalizability, and the limitation of the DM effective field theory (EFT) or simplified models for DM searches at high energy colliders, including the role of dark Higgs boson and dark gauge bosons.


Publication(career)
NUMBER  
AUTHOR  Ko, P.; Li, Gang; Li, Jinmian 
TITLE  Impact of the 125 GeV Higgs boson on singlet fermion dark matter searches at the LHC 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D, 98(5), 55031, 2018 
ABSTRACT  The search for singlet fermion dark matter at highenergy colliders is commonly analyzed with a singlet scalar mediator, which however violates the standard model (SM) gauge invariance, renormalizability and unitarity. These problems can be cured by introducing a mixing between the singlet scalar s and the SM Higgs boson h. Thus one has to consider two scalar mediators h(1) and h(2), where h(1) is identified as the discovered 125 GeV Higgs boson. As a specific example, we consider the dark matter (DM) search in the t (t) over bar + is not an element of(T) channel. According to the masses of dark matter and two scalar mediators, we classify the process into four cases. By investigating the total cross sections and differential distributions, we find that the contribution of the 125 GeV Higgs boson h(1) cannot be neglected in all cases and can even dominate once h(1) is on shell in dark matter production. Further, we study the impact of h(1) on the LHC bounds of dark matter searches in the hadronic and semileptonic channels with the integrated luminosity of 36 fb(1). Finally we make a brief comment that h(1) should be also considered in the vector DM search at highenergy colliders.


Publication(career)
NUMBER  
AUTHOR  Baek, Seungwon; Ko, Pyungwon; Wu, Peiwen 
TITLE  Heavy quarkphilic scalar dark matter with a vectorlike fermion portal 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, 7, 8, 2018 
ABSTRACT  The absence of confirmed signal in dark matter (DM) direct detection (DD) may suggest weak interaction strengths between DM and the abundant constituents inside nucleon, i.e. gluons and valence light quarks. In this work we consider a real scalar dark matter S interacting only with SU(2)(L) singlet Uptype quarks Ui, = uR, c(R), t(R) via a vector like fermion 0 which has the same quantum number as Ui. The DMnucleon scattering can proceed through both hmediated Higgs portal (HP) and psimediated vectorlike portal (VLP), in which HP can receive sizable radiative corrections through the new fermions. We first study the separate constraints on the new Yukawa couplings y(i) and find that the constraints of XENON1T results are strong on y(1) from VLP scattering and on y(3) from its radiative contributions to HP scattering. Since both DMlight quark interactions and HP have been well studied in the existing literature, we move forward to focus on DM heavy quark interactions. Since there is no valence c, t quark inside nucleons at mu(had) similar to 1 GeV, y(2), y(3) interactions are manifested in DMgluon scattering at loop level. We find that renormalization group equation (RGE) and heavy quark threshold effects are important if one calculates the DMnucleon scattering rate apsi at Mad 1 GeV while constructing the effective theory at mu(LEFT) similar to m(Z). For the benchmarks y(3) = 0.5, y(2) = 0.5,1, 3, combined results from Omega(DM)h(2) similar or equal to 0.12, XENON1T, FermiLAT, 13 TeV LHC data have almost excluded m(s) < m(t)/2 when only DM{c, t} interactions are considered. FCNC of top quark can be generated at both tree level t > psi(*),S > cSS and loop level t > c + gamma/g/Z, of which the branching fractions are typically below 10(9) after passing the other constraints, which are still safe from the current top quark width measurements.


Publication(career)
NUMBER  P18013 
AUTHOR  Hashino, Katsuya; Kakizaki, Mitsuru; Kanemura, Shinya; Ko, Pyungwon; Matsui, Toshinori 
TITLE  Gravitational waves from first order electroweak phase transition in models with the U(1)(X) gauge symmetry 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, 6, 88, 2018 
ABSTRACT  We consider a standard model extension equipped with a dark sector where the U(1)(X) Abelian gauge symmetry is spontaneously broken by the dark Higgs mechanism. In this framework, we investigate patterns of the electroweak phase transition as well as those of the dark phase transition, and examine detectability of gravitational waves (GWs) generated by such strongly first order phase transition. It is pointed out that the collider bounds on the properties of the discovered Higgs boson exclude a part of parameter space that could otherwise generate detectable GWs. After imposing various constraints on this model, it is shown that GWs produced by multistep phase transitions are detectable at future spacebased interferometers, such as LISA and DECIGO, if the dark photon is heavier than 25 GeV. Furthermore, we discuss the complementarity of dark photon searches or dark matter searches with the GW observations in these models with the dark gauge symmetry.


Publication(career)
NUMBER  P17047 
AUTHOR  Kang, Zhaofeng; Ko, P.; Matsui, Toshinori 
TITLE  Strong first order EWPT & strong gravitational waves in Z(3)symmetric singlet scalar extension 
ARCHIVE  arXiv:1706.09721 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS no.2, 115. 2018. 
ABSTRACT  

Publication(career)
NUMBER  Q16012 
AUTHOR  Ko, P.; Natale, Alexander; Park, Myeonghun; Yokoya, Hiroshi 
TITLE  Simplified DM models with the full SM gauge symmetry: the case of tchannel colored scalar mediators 
ARCHIVE  arXiv:1605.07058 
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS no.1, 86. 2017. 
ABSTRACT  

Publication(career)
NUMBER  Q16017 
AUTHOR  Kim, Jinsu; Ko, Pyungwon; Park, WanIl 
TITLE  Higgsportal assisted Higgs inflation with a sizeable tensortoscalar ratio 
ARCHIVE  1405.1635 
FILE  
JOURNAL  JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS no.2, 3. 2017 
ABSTRACT  

Publication(career)
NUMBER  P16076 
AUTHOR  Ko, P.; Li, Jinmian 
TITLE  Interference effects of two scalar boson propagators on the LHC search for the singlet fermion DM 
ARCHIVE  arXiv:1610.03997 
FILE  
JOURNAL  PHYSICS LETTERS B v.765, 5361p. 2017. 
ABSTRACT  

Publication(career)
NUMBER  P16027 
AUTHOR  Bi, XiaoJun; Kang, Zhaofeng; Ko, P.; Li, Jinmian; Li, Tianjun 
TITLE  Asymmetric dark matter bound state 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D v.95(4), 043540. 2017. 
ABSTRACT  

Publication(career)
NUMBER  P16036 
AUTHOR  Hagiwara, Kaoru; Ko, Pyungwon; Okamura, Naotoshi; Takaesu, Yoshitaro 
TITLE  Revisiting T2KK and T2KO physics potential and nu mu(nu)overbar mu beam ratio 
ARCHIVE  
FILE  
JOURNAL  EUROPEAN PHYSICAL JOURNAL C v.77(3), 138. 2017. 
ABSTRACT  

Publication(career)
NUMBER  P16065 
AUTHOR  Hashino, Katsuya; Kakizaki, Mitsuru; Kanemura, Shinya; Ko, Pyungwon; Matsui, Toshinori 
TITLE  Gravitational waves and Higgs boson couplings for exploring first order phase transition in the model with a singlet scalar field 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B v.766, 4954p. 2017. 
ABSTRACT  

Publication(career)
NUMBER  P17004 
AUTHOR  Baek, Seungwon; Ko, P.; Li, Jinmian 
TITLE  Minimal renormalizable simplified dark matter model with a pseudoscalar mediator 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D v.95(7), 075011. 2017. 
ABSTRACT  

Publication(career)
NUMBER  P16074 
AUTHOR  Ko, P.; Tang, Yong 
TITLE  Residual nonAbelian dark matter and dark radiation 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B v.768,1217p. 2017. 
ABSTRACT  

Publication(career)
NUMBER  P17010 
AUTHOR  Ko, P.; Nomura, Takaaki; Okada, Hiroshi 
TITLE  Explaining B > K(*())l(+)l() anomaly by radiatively induced coupling in U(1)(mutau) gauge symmetry 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D v.95(11), 111701.2017. 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P.; Yu, Chaehyun; Yuan, TzuChiang 
TITLE  Probing a new strongly interacting sector via composite diboson resonances 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D v.95(11), 115034. 2017. 
ABSTRACT  

Publication(career)
NUMBER  P17015 
AUTHOR  Ko, P.; Omura, Yuji; Shigekami, Yoshihiro; Yu, Chaehyun 
TITLE  LHCb anomaly and B physics in flavored Z models with flavored Higgs doublets 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D v.95(11), 115040. 2017 
ABSTRACT  

Publication(career)
NUMBER  P17007 
AUTHOR  Ko, P.; Nomura, Takaaki; Okada, Hiroshi 
TITLE  A flavor dependent gauge symmetry, predictive radiative seesaw and LHCb anomalies 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B v.772, 547552p. 2017 
ABSTRACT  

Publication(career)
NUMBER  P17033 
AUTHOR  Kamon, Teruki; Ko, P.; Li, Jinmian 
TITLE  Characterizing Higgs portal dark matter models at the ILC 
ARCHIVE  
FILE  
JOURNAL  EUROPEAN PHYSICAL JOURNAL C. v.77(9), 652. 2017. 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P.; Nagata, Natsumi; Tang, Yong 
TITLE  Hidden charged dark matter and chiral dark radiation 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B v.773, 513520p. 2017. 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P.; Nomura, Takaaki 
TITLE  Phenomenology of dark matter in chiral U(1)(X) dark sector 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW (2016) D94 no.11 115015 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Kang, Zhaofeng; Ko, P.; Li, Jinmian 
TITLE  New avenues to heavy righthanded neutrinos with pair production at hadronic colliders 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D93 (2016) no. 7, 075037 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Cheung, Kingman; Ko, P.; Lee, Jae Sik; Park, Jubin; Tseng, PoYan 
TITLE  Higgs precision study of the 750 GeV diphoton resonance and the 125 GeV standard model Higgs boson with Higgssinglet mixing 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D94 (2016) no.3, 033010 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P.; Nomura, Takaaki; Okada, Hiroshi; Orikasa, Yuta 
TITLE  Confronting a new threeloop seesaw model with the 750 GeV diphoton excess 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D v.94 no.1 (2016) 013009 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  XiaoGang He, Pyungwon Ko 
TITLE  Flavor SU (3) properties of beauty tetraquark states with three different light quarks 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B v.761 p.9297 (2016) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P.; Nomura, Takaaki 
TITLE  Dark sector shining through 750 GeV dark Higgs boson at the LHC 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B v.758 p.205211 (2016) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Baek, Seungwon; Ko, P.; Park, Myeonghun; Park, WanIl; Yu, Chaehyun 
TITLE  Beyond the dark matter effective field theory and a simplified model approach at colliders 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B v.756 p.289294 (2016) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P.; Tang, Yong 
TITLE  Dark Higgs channel for Fermi GeV gammaray excess 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS 2 (2016) 011 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Baek, Seungwon; Ko, Pyungwon; Wu, Peiwen 
TITLE  Topphilic scalar Dark Matter with a vectorlike fermionic top partner 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS 10 (2016) 117 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P.; Yokoya, Hiroshi 
TITLE  Search for Higgs portal DM at the ILC 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS 8 (2016) 109 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P.; Omura, Yuji; Yu, Chaehyun 
TITLE  Diphoton excess at 750 GeV in leptophobic U(1) model inspired by E6 GUT 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS 4 (2016) 098 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Hatanaka, Hisaki; Jung, DongWon; Ko, Pyungwon 
TITLE  AdS/QCD approach to the scaleinvariant extension of the standard model with a strongly interacting hidden sector 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS 1608 (2016) 094 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Yong Tang 
TITLE  Light dark photon and fermionic dark radiation for the Hubble constant and the structure formation 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B 762 (2016) 462 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Kang, Zhaofeng; Ko, P.; Li, Jinmian 
TITLE  New Physics Opportunities in the Boosted DiHiggsBoson Plus Missing Transverse Energy Signature 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW LETTERS v.116 no.13 (2016) 131801 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P; Nomura, T 
TITLE  SU(2)(L) x SU(2)(R) minimal dark matter with 2 TeV W 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B, v.753 (2016) 612618 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P; Tang, Y 
TITLE  IceCube events from heavy DM decays through the righthanded neutrino portal 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B, v.751 (2015) 8188 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Cheung, K; Ko, P; Lee, JS; Tseng, PY 
TITLE  Bounds on Higgsportal models from the LHC Higgs data 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, v.10 (2015) 057 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Baek, S; Ko, P; Park, WI 
TITLE  Local Z(2) scalar dark matter model confronting galactic GeVscale gammaray 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B, v.747 (2015) 255259 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Guo, J; Kang, ZF; Ko, P; Orikasa, Y 
TITLE  Accidental dark matter: Case in the scale invariant local B  L model 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D, v.91 no.11 (2015) 115017 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P; Omura, Y; Yu, C 
TITLE  Higgs and dark matter physics in the typeII twoHiggsdoublet model inspired by E6 GUT 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, v.6 (2015) 034 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Kang, ZF; Ko, P; Li, TJ; Liu, YD 
TITLE  Natural Xray lines from the low scale supersymmetry breaking 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B, v.742 (2015) 249255 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P; Tang, Y 
TITLE  AMS02 positron excess from decaying fermion DM with local dark gauge symmetry 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B, v.741 (2015) 284289 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P; Tang, Y 
TITLE  Galactic center gammaray excess in hidden sector DM models with dark gauge symmetries: local Z(3) symmetry as an example 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, v.1 (2015) 023 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P; Tang, Y 
TITLE  nu Lambda MDM: A model for sterile neutrino and dark matter reconciles cosmological and neutrino oscillation data after BICEP2 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B, v.739 (2014) 6267 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P; Omura, Y; Yu, C 
TITLE  Dark matter and dark force in the typeI inert 2HDM with local U(1)(H) gauge symmetry 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, v.11 (2014) 054 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Baek, S; Ko, P; Park, WI 
TITLE  Hidden sector monopole, vector dark matter and dark radiation with Higgs portal 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, v.10 (2014) 067 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Baek, S; Ko, P; Okada, H; Senahaa, E 
TITLE  Can ZeeBabu model implemented with scalar dark matter explain both FermiLAT 130 GeV gammaray excess and neutrino physics? 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, v.9 (2014) 153 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Baek, S; Ko, P; Park, WI 
TITLE  Invisible Higgs decay width versus dark matter direct detection cross section in Higgs portal dark matter models 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D, v. 90 no.5 (2014) 055014 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P; Park, WI; Tang, Y 
TITLE  Higgs portal vector dark matter for GeV scale gammaray excess from galactic center 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, v.9 (2014) 013 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Jung, S; Ko, P; Yoon, YW; Yu, C 
TITLE  Renormalization groupinduced phenomena of top pairs from fourquark effective operators 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, v.8 (2014) 120 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Jung, S; Ko, P; Yoon, YW; Yu, C 
TITLE  Correlation of top asymmetries: Loop versus tree origins 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D, v.90 no.3 (2014) 034007 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Baek, S; Ko, P; Park, WI; Tang, Y 
TITLE  Indirect and direct signatures of Higgs portal decaying vector dark matter for positron excess in cosmic rays 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, v.6 (2014) 046 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P; Tang, Y 
TITLE  Selfinteracting scalar dark matter with local Z(3) symmetry 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, v.5 (2014) 047 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Jung, DW; Ko, P 
TITLE  Higgsdilaton(radion) system confronting the LHC Higgs data 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B, v.732 (2014) 364372 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P; Omura, Y; Yu, C 
TITLE  Higgs phenomenology in TypeI 2HDM with U(1)(H) Higgs gauge symmetry 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, v.1 (2014) 016 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Baek, S; Ko, P; Park, WI 
TITLE  Singlet portal extensions of the standard seesaw models to a dark sector with local dark symmetry 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, v.7 (2013) 013 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Choi, S; Jung, S; Ko, P 
TITLE  Implications of LHC data on 125 GeV Higgslike boson for the Standard Model and its various extensions 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, v.10 (2013) 225 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Baek, S; Ko, P; Park, WI; Senaha, E 
TITLE  Higgs portal vector dark matter: revisited 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, v.5 (2103) 036 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P; Omura, Y; Yu, C 
TITLE  B > D(*())tau nu and B > tau nu in chiral U(1) models with flavored multi Higgs doublets 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, v.3 (2013) 151 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P; Omura, Y; Yu, C 
TITLE  Top A(FB) at the Tevatron vs. charge asymmetry at the LHC in chiral U(1) flavor models with flavored Higgs doublets 
ARCHIVE  
FILE  
JOURNAL  EUROPEAN PHYSICAL JOURNAL C, v.73 no.1 (2013) 2269 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Seungwon Baek, P. Ko, WanIl Park, Eibun Senaha 
TITLE  Vacuum structure and stability of a singlet fermion dark matter model with a singlet scalar messenger 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, v.11 (2012) 116 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P; Omura, Y; Yu, C 
TITLE  A resolution of the flavor problem of two Higgs doublet models with an extra U(1)(H) symmetry for Higgs flavor 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B, v.717 no.13 (2012) 202206 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Alves, D; ArkaniHamed, N; Arora, S; Bai, Y; Baumgart, M; Berger, J; Buckley, M; Butler, B; Chang, S; Cheng, HC; Cheung, C; Chivukula, RS; Cho, WS; Cotta, R; DAlfonso, M; El Hedri, S; Essig, R; Evans, JA; Fitzpatrick, L; Fox, P; Franceschini, R; Fre 
TITLE  Simplified models for LHC new physics searches 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF PHYSICS GNUCLEAR AND PARTICLE PHYSICS, v.39 no.10 (2012) 105005 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P; Omura, Y; Yu, C 
TITLE  Top forwardbackward asymmetry and the CDF Wjj excess in leptophobic U(1) flavor models 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D, v.85 no.11 (2012) 115010 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P; Omura, Y; Yu, C 
TITLE  Dijet resonance from leptophobic Z and light baryonic cold dark matter 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B, v.710 no.1 (2012) 197200 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Gondolo, P; Ko, P; Omura, Y 
TITLE  Light dark matter in leptophobic Z models 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D, v.85 no.3 (2012) 035022 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Jung, DW; Ko, P; Lee, JS 
TITLE  Mass dependent top forwardbackward asymmetry in the effective Lagrangian approach: Addendum to Model independent analysis of the forwardbackward asymmetry of top quark production at the Tevatron 
ARCHIVE  
FILE  
JOURNAL  PHYSICS LETTERS B, v.708 no.12 (2012) 157161 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Baek, S; Ko, P; Park, WI 
TITLE  Search for the Higgs portal to a singlet fermionic dark matter at the LHC 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, v.2 (2012) 047 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Ko, P; Omura, Y; Yu, C 
TITLE  Chiral U(1) flavor models and flavored Higgs doublets: the top FB asymmetry and the Wjj 
ARCHIVE  
FILE  
JOURNAL  JOURNAL OF HIGH ENERGY PHYSICS, v.1 (2012) 147 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Jung, DW; Ko. P; Lee, JS 
TITLE  Possible common origin of the top forwardbackward asymmetry and the CDF Wjj excess 
ARCHIVE  
FILE  
JOURNAL  PHYSICAL REVIEW D, v.84 no.5 (2011) 055027 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Taeil Hur, P. Ko 
TITLE  Scale invariant extension of the standard model with strongly interacting hidden sector 
ARCHIVE  arXiv:1103.2571 
FILE  
JOURNAL  Phys.Rev.Lett.106:141802,2011 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Pyungwon Ko, Yuji Omura 
TITLE  Supersymmetric U(1)B x U(1)L model with leptophilic and leptophobic cold dark matters 
ARCHIVE  arXiv:1012.4679 
FILE  
JOURNAL  Phys.Lett.B701:363366,2011 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Taeil Hur, DongWon Jung, P. Ko, Jae Yong Lee 
TITLE  Electroweak symmetry breaking and cold dark matter from strongly interacting hidden sector 
ARCHIVE  arXiv:0709.1218 [hepph] 
FILE  
JOURNAL  Phys. Lett. B696 (2011) 262 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  DongWon Jung, P. Ko, Jae Sik Lee 
TITLE  Longitudinal top polarization as a probe of a possible origin of forwardbackward asymmetry of the top quark at the Tevatron 
ARCHIVE  arXiv:1011.5976 
FILE  
JOURNAL  Phys.Lett.B701:248254,2011 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Chaehyun Yu, Jungil Lee 
TITLE  Inclusive doublequarkonium production at the Large Hadron Collider 
ARCHIVE  arXiv:1007.3095 
FILE  
JOURNAL  JHEP 1101:070,2011 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Chaehyun Yu, Jungil Lee 
TITLE  p p > J/¡¬psi + ¡¬Upsilon + X as a clean probe to the quarkonium production mechanism 
ARCHIVE  arXiv:1006.3846 
FILE  
JOURNAL  Phys.Rev.D83:054015,2011 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  DongWon Jung, Pyungwon Ko, Jae Sik Lee, SooHyeon Nam 
TITLE  Model independent analysis of the forwardbackward asymmetry of top quark production at the Tevatron 
ARCHIVE  
FILE  
JOURNAL  Phys. Lett. B691 (2010) 238 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Jungil Lee, Chaehyun Yu 
TITLE  Double quarkonium production at the LHC 
ARCHIVE  
FILE  
JOURNAL  PoS ICHEP2010:220,2010 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Jaehyeon Park 
TITLE  Addendum to: Implications of the measurements of $B_sB_s bar$ mixing on SUSY models 
ARCHIVE  arXiv:1006.5821 
FILE  
JOURNAL  Phys.Rev.D82:117701,2010 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  DongWon Jung, P. Ko, Jae Sik Lee, Soohyeon Nam 
TITLE  Model independent analysis of the forwardbackward asymmetry of top quark production at the Tevatron 
ARCHIVE  arXiv:0912.1105 
FILE  
JOURNAL  Phys.Lett.B691:238242,2010 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Pyungwon Ko 
TITLE  Electroweak symmetry breaking and cold dark matter from hidden sector strong interaction 
ARCHIVE  
FILE  
JOURNAL  AIP Conf.Proc.1178:3743,2009 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Yutaka Hosotani, Pyungwon Ko, Minoru Tanaka 
TITLE  Stable Higgs Bosons as Cold Dark Matter 
ARCHIVE  arXiv:0908.0212 
FILE  
JOURNAL  Phys.Lett.B680:179183,2009 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Seungwon Baek, Pyungwon Ko 
TITLE  Phenomenology of U(1)(L(mu)L(tau)) charged dark matter at PAMELA and colliders 
ARCHIVE  arXiv:0811.1646 
FILE  
JOURNAL  JCAP 0910:011,2009 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Jaehyeon Park 
TITLE  Implications of the measurements of $B_s$  $bar{B}_s$ mixing on SUSY models 
ARCHIVE  arXiv:0809.0705 
FILE  
JOURNAL  Phys.Rev.D80:035019,2009 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Deog Ki Hong, (ed.), Pyungwon Ko, (ed.) 
TITLE  Supersymmetry and the unification of fundamental interactions 
ARCHIVE  
FILE  
JOURNAL  AIP Conf. Proc. 1078 (2008) 644 p 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Pyungwon Ko, Jaehyeon Park and Masahiro Yamaguchi 
TITLE  Sflavor mixing map viewed from a high scale in supersymmetric SU(5) 
ARCHIVE  arXiv:0809.2784 
FILE  
JOURNAL  JHEP 0811, 051 (2008) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Youngman Kim, P. Ko and XiaoHong Wu 
TITLE  Holographic QCD beyond the leading order 
ARCHIVE  arXiv:0804.2710 
FILE  
JOURNAL  JHEP 0806, 094 (2008) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Pyungwon Ko 
TITLE  Electroweak symmetry breaking and cold dark matter from hidden sector technicolor 
ARCHIVE  arXiv:0801.4284 
FILE  
JOURNAL  Int. J. Mod. Phys. A23, 3348 (2008) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Nei Cipriano Ribeiro, Hiroshi Nunokawa, Takaaki Kajita, Shoei Nakayama, Pyungwon Ko, and Hisakazu Minakata 
TITLE  Probing nonstandard neutrino physics by two identical detectors with different baselines 
ARCHIVE  arXiv:0712.4314 
FILE  
JOURNAL  Phys. Rev. D77, 073007 (2008) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  S.W.Ham, Taeil Hur, P. Ko and S.K.Oh 
TITLE  Neutral scalar Higgs bosons in the USSM at the LHC 
ARCHIVE  arXiv:0801.2361 
FILE  
JOURNAL  J. Phys. G35, 095007 (2008) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Taeil Hur, P. Ko and XiaoHong Wu 
TITLE  Antisymmetric rank2 tensor unparticle physics 
ARCHIVE  arXiv:0709.0629 
FILE  
JOURNAL  Phys. Rev. D76, 096008 (2007) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Pyungwon Ko, Tatsuo Kobayashi and Jaehyeon Park 
TITLE  Stringderived D4 flavor symmetry and phenomenological implications 
ARCHIVE  arXiv:0704.2807 
FILE  
JOURNAL  Phys. Rev. D76, 035005 (2007) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko 
TITLE  Implications of the recent measurement of Bs  Bs mixing on SUSY models 
ARCHIVE  
FILE  
JOURNAL  Nucl. Phys. Proc. Suppl. 163, 185 (2007) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Byungchul Chung, Kang Young Lee, DongWon Jung, Pyungwon Ko 
TITLE  Partially composite twoHiggs doublet model 
ARCHIVE  hepph/0703223 
FILE  
JOURNAL  JHEP 0605, 010 (2006) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  ChaoShang Huang, Pyungwon Ko, XiaoHong Wu, YaDong Yang 
TITLE  MSSM anatomy of the polarization puzzle in B ¡æ ϕK* decays 
ARCHIVE  hepph/0511129 
FILE  
JOURNAL  Phys. Rev. D73, 034026 (2006) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Seungwon Baek, Yeong Gyun Kim and P. Ko 
TITLE  Bs ! ¥ì+¥ì and the upwardgoing muon flux from the WIMP annihilation in the sun or the earth 
ARCHIVE  hepph/0506115 
FILE  
JOURNAL  JHEP 0511, 007 (2005) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  S. Baek, D.G. Cerdeno, Y.G. Kim, P. Ko and C. Munoz 
TITLE  Direct detection of neutralino dark matter in supergravity 
ARCHIVE  hepph/0505019 
FILE  
JOURNAL  JHEP 0506, 017 (2005) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Jaehyeon Park and A. Masiero 
TITLE  Re (ϵ¡Ç/ϵK ) vs. Bd ¡æ ϕKS CP asymmetry 
ARCHIVE  hepph/0503102 
FILE  
JOURNAL  Phys. Rev. D72, 016004 (2005) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Pyungwon Ko, Tatsuo Kobayashi and Jaehyeon Park 
TITLE  Lepton masses and mixing angles from heterotic orbifold models 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. D71, 095010 (2005) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Daekyoung Kang, JongWan Lee, Jungil Lee, Taewon Kim and Pyungwon Ko 
TITLE  Colorevaporationmodel calculation of e+e ¡æ J/¥÷ + cc + X at s = 10.6 GeV 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. D71, 094019 (2005) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Daekyoung Kang, JongWan Lee, Jungil Lee, Taewon Kim and Pyungwon Ko 
TITLE  Inclusive production of four charm hadrons in e+e annihilation at B factories 
ARCHIVE  hepph/0412224 
FILE  
JOURNAL  Phys. Rev. D71, 071501 (2005) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Seungwon Baek, Yeong Gyun Kim and P. Ko 
TITLE  Neutralino dark matter scattering and Bs ¡æ ¥ì+¥ì in SUSY models 
ARCHIVE  hepph/0406033 
FILE  
JOURNAL  JHEP 0502, 067 (2005) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Taewon Kim and P. Ko 
TITLE  Dipion invariant mass spectrum in X(3872) ¡æ J/¥÷¥ð¥ð 
ARCHIVE  hepph/0405265 
FILE  
JOURNAL  Phys. Rev. D71, 034025 (2005); Erratumibid. D71, 099902 (2005) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Jungil Lee, Taekoon Lee and Jaehyeon Park 
TITLE  Chiral perturbation theory for pentaquark baryons and its applications 
ARCHIVE  hepph/0312147 
FILE  
JOURNAL  Phys.Lett.B611, 87 (2005) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  G.L. Kane, P. Ko, Haibin Wang, C. Kolda, Jaehyeon Park and LianTao Wang 
TITLE  Bd ¡æ ϕKS and supersymmetry 
ARCHIVE  hepph/0212092 
FILE  
JOURNAL  Phys. Rev. D70, 035015 (2004) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  Pyungwon Ko, Tatsuo Kobayashi and Jaehyeon Park 
TITLE  Quark masses and mixing angles in heterotic orbifold models 
ARCHIVE  hepph/0406041 
FILE  
JOURNAL  Phys. Lett. B598, 263 (2004) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, G.L. Kane, P. Ko, Haibin Wang, C. Kolda, Jaehyeon Park, LianTao Wang 
TITLE  Bd ¡æ ϕKS CP asymmetries as an important probe of supersymmetry 
ARCHIVE  hepph/0304239 
FILE  
JOURNAL  Phys. Rev. Lett. 90 141803 (2003) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Seungwon Baek and Wan Young Song 
TITLE  SUSY breaking mediation mechanisms and (g  2)¥ì, B ¡æ Xs¥ã, B ¡æ Xsl+l and Bs ¡æ ¥ì+¥ì 
ARCHIVE  hepph/0208112 
FILE  
JOURNAL  JHEP 0303, 054 (2003) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Jaehyeon Park 
TITLE  CP violations in the K and B meson systems in the SUSY models with (S3)3 flavor summetry 
ARCHIVE  hepph/0207016 
FILE  
JOURNAL  JHEP 0209, 017 (2002) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, P. Ko and Jaehyeon Park 
TITLE  Is large SUSY CP violation compatible with the current data? 
ARCHIVE  
FILE  
JOURNAL  J. Korean Phys. Soc. 41, 27 (2002) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Seungwon Baek and Wan Young Song 
TITLE  Implications on SUSY breaking mediations mechanisms from observing Bs ¡æ ¥ì+¥ì and the muon (g  2) 
ARCHIVE  hepph/0205259 
FILE  
JOURNAL  Phys. Rev. Lett.89, 271801 (2002) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Jaehyeon Park and G. Kramer 
TITLE  B0  B0 mixing, B ¡æ J/¥÷Ks and B ¡æ Xd ¥ã in general MSSM 
ARCHIVE  hepph/0206297 
FILE  
JOURNAL  Eur. Phys. J.C25, 615 (2002) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, S.Y. Choi, Byungchul Chung and Jae Sik Lee 
TITLE  CP violating chargino contributions to the Higgs coupling to photon pairs in the decoupling regime of Higgs sector 
ARCHIVE  hepph/0206025 
FILE  
JOURNAL  Phys. Rev. D 66, 016009 (2002) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, S. Baek and Jaehyeon Park 
TITLE  Muon anomalous magnetic moment from effective supersymmetry 
ARCHIVE  hepph/0203251 
FILE  
JOURNAL  Eur. Phys. J. C 24, 613618 (2002) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, S. Baek and Hong Seok Lee 
TITLE  Muon anomalous magnetic moment, B ¡æ Xs¥ã and dark matter detection in the string models with dilaton domination 
ARCHIVE  hepph/0103218 
FILE  
JOURNAL  Phys. Rev. D65, 035004 (2002) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, S. Baek, N.G. Deshpande and X.G. He 
TITLE  Muon anomalous g  2 and gauged Lɥ  L¥ó models 
ARCHIVE  hepph/0104141 
FILE  
JOURNAL  Phys. Rev. D 64, 055006 (2001) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, S. Baek, J.H. Jang and J.H. Park 
TITLE  Gluino squark contributions to CP violations in the kaon system 
ARCHIVE  hepph/0105028 
FILE  
JOURNAL  Nucl. Phys. B 609, 442468 (2001) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Sae Byok Bae, Hong Seok Lee, Jungil Lee 
TITLE  Phenomenology of the radion in the RandallSundrum scenario at colliders 
ARCHIVE  hepph/0002224 
FILE  
JOURNAL  Phys. Lett. B 487, 299305 (2000) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, S. Baek, J.H. Jang and J.H. Park 
TITLE  Fully supersymmetric CP violations in the kaon system 
ARCHIVE  hepph/9907572 
FILE  
JOURNAL  Phys. Rev. D 62, 117701 (2000) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, S. Baek 
TITLE  Effects of supersymmetric CP violating phases in B ¡æ Xs l+l and ϵK 
ARCHIVE  hepph/9904283 
FILE  
JOURNAL  Phys. Lett. B 462, 95102 (1999) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, S. Baek 
TITLE  Probing SUSY induced CP violations at B factories 
ARCHIVE  hepph/9812229 
FILE  
JOURNAL  Phys. Rev. Lett. 83, 488491 (1999) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Y.G. Kim. J. S. Lee and K. Y. Lee 
TITLE  Complete analysis of photino mediated lepton flavor violations in generalized supersymmetric models 
ARCHIVE  hepph/9811211 
FILE  
JOURNAL  Phys. Rev. D 59, 055018 (1999) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, J.H. Jang, Y.G. Kim 
TITLE  B decays into two light pseudoscalar mesons and possible effects of enhanced b ¡æ sg 
ARCHIVE  hepph/9810366 
FILE  
JOURNAL  Phys.Rev.D 59, 034025 (1999) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Y.G. Kim and J.S. Lee 
TITLE  Possible new physics signals in B ¡æ Xs¥ã and B ¡æ Xsl+l 
ARCHIVE  hepph/9810336 
FILE  
JOURNAL  Nucl. Phys.B 544, 6488 (1999) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Jungil Lee and H.S. Song 
TITLE  Testing J/¥÷ production mechanisms in B ¡æ J/¥÷ + X 
ARCHIVE  
FILE  
JOURNAL  J. Kor. Phys. Soc. 34, 301 (1999) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, J.H. Jang 
TITLE  A new method for extracting the weak phase ¥ã from B ¡æ DK(*) decays 
ARCHIVE  hepph/9807496 
FILE  
JOURNAL  Phys. Rev. D 58, 111302 (1998) (Rapid Communications) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, K. Kang, S.K. Kang, J.E. Kim 
TITLE  Mass matrix ansatz for degenerate neutrinos consistent with solar and atmospheric neutrino data 
ARCHIVE  
FILE  
JOURNAL  Phys. Lett. B 442, 249254 (1998) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, S. Baek, J. Lee and H.S. Song 
TITLE  Polarized J/¥÷ production at CLEO 
ARCHIVE  hepph/9804455 
FILE  
JOURNAL  J. Kor. Phys. Soc. 33, 97 (1998) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, A. Ali, J. Chay and C. Greub 
TITLE  Contribution of b ¡æ sgg through the QCD anomaly in exclusive decays B¡¾ ¡æ (¥ç¡Ç , ¥ç)(K¡¾,K*¡¾) and B0 ¡æ (¥ç¡Ç , ¥ç)(K0,K0) 
ARCHIVE  hepph/9810300 
FILE  
JOURNAL  Phys. Lett.B 424, 161174 (1998) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Jihn E. Kim 
TITLE  Supersymmetric interpretation of highQ2 HERA events and other related topics 
ARCHIVE  hepph/9706387 
FILE  
JOURNAL  Phys. Rev. D 57, 489495 (1998) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Kyungsik Kang, Sinkyu Kang and Jihn E Kim 
TITLE  Almost mally broken permutation symmetry for neutrino mass matrix 
ARCHIVE  hepph/9611369 
FILE  
JOURNAL  Mod. Phys. Lett. A 12, 11751184 (1997) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Jihn E. Kim and DaeGyu Lee 
TITLE  More on R parity and lepton family number violating coupling from muon(ium) conversion, and tau and ¥ð0 decays 
ARCHIVE  hepph/9701381 
FILE  
JOURNAL  Phys. Rev. D 56, 100106 (1997) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Seungwon Baek, Jungil Lee, and H.S. Song 
TITLE  Coloroctet mechanism and J/¥÷ polarization at LEP 
ARCHIVE  hepph/9701208 
FILE  
JOURNAL  Phys. Rev. D 55, 68396843 (1997) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Jungil Lee and H.S. Song 
TITLE  Coloroctet mechanism in the inclusive D wave charmonium productionsin B decays 
ARCHIVE  hepph/9701235 
FILE  
JOURNAL  Phys. Lett. B 395, 107112 (1997) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Seungwon Baek, Jungil Lee and H.S. Song 
TITLE  Coloroctet heavy quarkonium productions in Z0 decays at LEP 
ARCHIVE  hepph/9607236 
FILE  
JOURNAL  Phys. Lett. B 389, 609615 (1996) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Jungil Lee and H.S. Song 
TITLE  Coloroctet mechanism in ¥ã + p ¡æ J/¥÷ +X 
ARCHIVE  hepph/9602223 
FILE  
JOURNAL  Phys. Rev. D 53, 43124325 (1996) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Kyungsik Kang and Jihn E. Kim 
TITLE  A simple modification of the maximal mixing scenario for three light neutrinos 
ARCHIVE  hepph/9503436 
FILE  
JOURNAL  Z. Phys. C 72, 671675 (1996) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, J.K. Kim, K.Y. Lee and S. Rudaz 
TITLE  a1 (1260) contributions to photon and dilepton productions from hot hadronic matter : revisited 
ARCHIVE  hepph/9602293 
FILE  
JOURNAL  Phys. Rev. D 53, 47874792 (1996) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Jungil Lee and H.S. Song 
TITLE  Chiral perturbation theory vs. vector meson dominance in the decays ϕ ¡æ ¥ñ¥ã¥ã and ϕ ¡æ ¥ø¥ã¥ã 
ARCHIVE  hepph/9510205 
FILE  
JOURNAL  Phys. Lett. B 366, 287292 (1996) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Jungil Lee and H.S. Song 
TITLE  Inclusive Swave charmonium productions in B decays 
ARCHIVE  hepph/9510202 
FILE  
JOURNAL  Phys. Rev. D 53, 14091415 (1996) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko 
TITLE  Estimates of ¥öc(2P) production rates in B and r(1S) decays 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. D 52, 31083110 (1995) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko 
TITLE  Search for ¥ç¡Çc and hc(1P1) states in the e+e annihilations 
ARCHIVE  hepph/9505299 
FILE  
JOURNAL  Phys. Rev. D 52, 17101712 (1995) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, K.Y. Lee and J.K. Kim 
TITLE  KLe5 decay as a background to KL ¡æ ¥ð0¥ì¡¾e∓ 
ARCHIVE  hepph/9502320 
FILE  
JOURNAL  Phys. Rev. D 51, 34553458 (1995) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko 
TITLE  ¥ç ¡æ ¥ð0¥ã¥ã and ¥ã¥ã ¡æ ¥ð0¥ð0 in O(p6) chiral perturbation theory 
ARCHIVE  hepph/9503253 
FILE  
JOURNAL  Phys. Lett. B 349, 555560 (1995) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, C.S. Kim, D.S. Hwang and W. Namgung 
TITLE  New approach for measuring Vbu at future Bfactories 
ARCHIVE  hepph/9406251 
FILE  
JOURNAL  Phys. Rev. D 50, 57625766 (1994) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, S.Chakravarty and S.M. Kim 
TITLE  Final state ¥ð¥ð interactions in r(3S) ¡æ r(1S) ¥ð¥ð 
ARCHIVE  hepph/9310376 
FILE  
JOURNAL  Phys. Rev. D 50, 389394 (1994) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Serge Rudaz 
TITLE  Phenomenology of scalar and vector mesons in the linear sigma model 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. D 50, 68776894 (1994) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko 
TITLE  Testing the SU(3)L ¡¿ U(1)X model from muonium ¡æ antimuonium conversion 
ARCHIVE  
FILE  
JOURNAL  Il Nuovo Cimento 107 A, 809811 (1994) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, Changju Kim, Choonkyu Lee, BumHoon Lee and Hyunsoo Min 
TITLE  Schrodinger fields on the plane with [U(1)]N ChernSimons interactions and Generalized selfdual solitons 
ARCHIVE  hepth/9303131 
FILE  
JOURNAL  Phys. Rev. D 48, 18211840 (1993) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, S. Chakravarty and S.M. Kim 
TITLE  Is Upsilon (3S) a pure Swave ? 
ARCHIVE  hepph/9301249 
FILE  
JOURNAL  Phys. Rev. D 48, 12121219 (1993) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko 
TITLE  Radiative and hadronic decays of the charmonium 1P1(cc) state 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. D 47, 28372839 (1993) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, S. Chakravarty 
TITLE  ¥ð¥ð spectrum in r(3S) ¡æ r(1S)¥ð¥ð 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. D 48, 12051211 (1993) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko 
TITLE  Contributions of the Codd axial vector resonances to ¥ç ¡æ ¥ð0¥ã¥ã and ¥ã¥ã ¡æ ¥ð0¥ð0 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. D 47, 39333937 (1993) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko 
TITLE  Isospin symmetry breaking Swave ¥ð¥ð form factor in KL ¡æ ¥ð0¥ð∓e¡¾(¥í) 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. D 47, 12501251 (1993) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko 
TITLE  Branching ratio of r(1D) ¡æ r(1S)¥ð¥ð 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. D 47, 208209 (1993) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko 
TITLE  Chiral loop contribution to D ¡æ K*l¥í 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. D 47, 1964{1972 (1993) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko 
TITLE  KL ¡æ ¥ð0¥ð∓e¡¾(¥í) and vector symmetry 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. D 46, 3813{3816 (1992) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko 
TITLE  KL ¡æ ¥ì+¥ì and related topics 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev.D 45, 174177 (1992) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko 
TITLE  Role of vector mesons in rare kaon decays 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. D 44, 139165 (1991) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, T.N. Truong 
TITLE  KL ¡æ 2¥ã and KL ¡æ ¥ð+¥ð¥ã decays 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev.D 43, R48 (1991) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, T.N. Truong 
TITLE  Analysis of 2¥ã and ¥ð+¥ð¥ã decays of ¥ç and ¥ç¡Ç using chiral anomalies 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. D 42, 24192422 (1990) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko 
TITLE  Vectormeson contributions to the processes ¥ã¥ã ¡æ ¥ð0¥ð0, ¥ð+¥ð,KL ¡æ ¥ð0¥ã¥ã and K+ ¡æ ¥ð+¥ã¥ã 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. D 41, 15311540 (1990) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, J.L. Rosner 
TITLE  Pionpair contribution to the decay KL ¡æ ¥ð0¥ã¥ã 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. D 40, 37753778 (1989) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  P. Ko, T. Lee 
TITLE  Twoloop renormalization of the Pontryagin density in the pure YangMills theory 
ARCHIVE  
FILE  
JOURNAL  Phys. Rev. D 36, 1943{1946 (1987) 
ABSTRACT  

Publication(career)
NUMBER  
AUTHOR  M.S. Thesis 
TITLE  Topologically nontrivial configurations in certain field theories 
ARCHIVE  
FILE  
JOURNAL  Seoul National University (1985) (unpublished) 
ABSTRACT  
 Office:1314 / TEL) 8229583738 / FAX) 8229583870
 Center for Advanced Computation, Korea Institute for Advanced Study
85 Hoegiro, Dongdaemungu, Seoul 02455, Korea