Universal features of BPS strings in six-dimensional SCFTs

Universal features of BPS strings in six-dimensional SCFTs

Blog Article

Abstract In theories with extended supersymmetry the protected observables of UV superconformal fixed points are found in a number of contexts to be encoded in the BPS solitons along an IR Coulomb-like DVD Parts phase.For six-dimensional SCFTs such a role is played by the BPS strings on the tensorial Coulomb branch.In this paper we develop a uniform description of the worldsheet theories of a BPS string for rank-one 6d SCFTs.These strings are the basic constituents of the BPS string spectrum of arbitrary rank six-dimensional models, which they generate by forming bound states.

Motivated by geometric engineering in F-theory, we describe the worldsheet theories of the BPS strings in terms of topologically twisted 4d N=2 $$ mathcal{N}=2 $$ theories in the presence of 1/2-BPS 2d (0, 4) defects.As the superconformal point of a 6d theory with gauge group G is approached, the resulting worldsheet theory flows to an N=0,4 $$ mathcal{N}=left(0, 4 ight) $$ NLSM with target the moduli space of one G instanton, together with a nontrivial left moving bundle characterized by the matter content of the six-dimensional model.We compute the anomaly polynomial and central charges of the NLSM, and argue that the 6d flavor symmetry F is realized as a current algebra on the string, whose level we compute.We find evidence that for generic theories the G dependence is captured at the level of the elliptic genus by characters of an affine Kac-Moody algebra at negative level, which we interpret as a subsector of the chiral algebra of the BPS string worldsheet theory.

We also find Rangehood Wall Vent Adaptor evidence for a spectral flow relating the R-R and NS-R elliptic genera.These properties of the string CFTs lead to constraints on their spectra, which in combination with modularity allow us to determine the elliptic genera of a vast number of string CFTs, leading also to novel results for 6d and 5d instanton partition functions.