|DATE||May 24 (Thu), 2018|
|TITLE||Universal features of 6d BPS strings|
The one-instanton sector of the BPS spectrum of 6d SCFTs on the tensor branch consists of non-critical strings, whose worldsheet dynamics are described by an interesting family of N=(0,4) CFTs. I will discuss how these CFTs share a number of features, including a uniform realization of their global symmetries at the level of chiral algebra in terms of Kac-Moody algebras at both positive and negative levels and the existence of a spectral flow symmetry on the chiral algebra. Among other things, this helps explain various properties of the elliptic genus which strongly constrain its form. Time permitting, I will discuss how these constraints, combined with a modular bootstrap approach, can be used to completely fix the elliptic genus for many of these theories.