Particle physics is the science of the fundamental particles and interactions of Nature.
A continuing series of efforts to probe deeper into the structure of matter in theories and experiments has resulted in a model of the fundamental particles and forces of matter, the Standard Model. During the last thirty years, the Standard Model has been tested in various ways and successful as it is in describing a vast amount of experimental data. Despite its great phenomenological success, the Standard Model is not regarded as the ultimate one. It provides no explanation of the scale of weak interactions, pattern of quark and lepton masses and mixings, the origin of CP violation, and particularly the origin of neutrino masses and dark matter.
The particle physics group of KIAS is pursuing search for some unknown ingredients of the Standard Model and new physics beyond the Standard Model by studying both the deep structure of the Standard Model and the general features that are required by some extensions of the Standard model, and possibly related with various cosmological and astrophysical aspects. The forthcoming LHC data will guide us in the establishment of the more fundamental theory of particle and the origin of electroweak symmetry breaking, in addition to further test of the Standard Model.
The suspersymmetry is one of the most promising extensions of the Standard Model. Supersymmetric standard model has a rich spectrum of new particles that are expected to have masses of the order of a few hundred GeV, and contains a stable neutral particle that is a natural candidate to account for the dark matter that is believed to pervade the whole of space.
Members of KIAS particle physics group are pursuing our understanding of all possible variants of weak scale supersymmetry which may manifest themselves in collider experiments such as LHC and Tevatron Run II. Particular interest is focused on the study of the properties of Higgs bosons in the supersymmetric models. Other topics of investigation within the supersymmetric models are collider signals for supersymmetric top, Higgs, neutrinos, dark matter, dynamical explanations for the masses and mixing patterns of quarks and leptons and their super-partners.
Another exciting ideas in theoretical physics is the existence of extra dimensions of spacetime, because it does not only inspire many SF writers but also requires us to understand the quantum gravity. Recently the idea of extra dimensions is revived in two different scenarios as a possible solution of the unnatural hierarchy of scales. One of the most interesting aspects of this picture is that it predicts remarkable new phenomena that will soon be tested experimentally. Many implications of this framework have been explored intensively, in collider signals, cosmological implications, astrophysical constraints and relations with string theories.
The observed neutrino masses and mixings and the existence of dark matter would be two most important pillars in establishing new physics beyond the Standard Model whose signature might be found at the LHC in the near future. Concerned with neutrino physics, KIAS particle physics group is working on confronting various theoretical possibilities of neutrino oscillation with the present experimental results. We also keep a substantial interest on how the current data from solar and atmospheric neutrino experiments as well as terrestrial experiments and astrophysical and cosmological observations such as the matter-antimatter asymmetry of the Universe can be accounted for in grand unified models and supersymmetric models. Identifying dark matter through various direct and indirect experiments as well as theoretical investigations is one of the key issues not only in cosmology and astrophysics but also in particle physics. Gravitational effect shows us that about 80 % of the matter in the Universe is made of some unknown non-atomic matter which requires new physics prescribing its mass and non-gravitational interactions and the origin of its cosmological abundance. It is one of our goals to identify what they are.