ON THE (0, 4) CONFORMAL FIELD THEORY OF THE THROAT

Abstract

In SO(32) heterotic string theory, the space–time at the core of N coincident NS five-branes is an infinite throat, ℝ×S3. As shown by Witten, the throat signals a singularity in the usual heterotic string conformal field theory and a nonperturbative USp (2N) gauge group appears, due to the N small instantons at the five-branes' core. Nevertheless, we look for some trace of the nonperturbative physics in the description of the heterotic string infinitely far down the throat. Our guide is a D1-brane probing N D5-branes in type I, which yields a (1+1)-dimensional (0, 4) supersymmetric model with ADHM data in its couplings, as shown by Douglas. The neighborhood of the classical boundary of the hypermultiplet moduli space of the theory flows to an exact conformal field theory description of the throat theory. Ironically, the remnant of the nonperturbative symmetry is indeed found in the conformal field theory, lurking in the structure of the partition function, and encoded in a family of deformations of the theory along flat directions. The deformations have an explicit description using the flow from type I theory, and have a hyper-Kähler structure. Similar results hold true for the analogous (4, 4) supersymmetric situation in type IIB theory, as is evident in the work of Diaconescu and Seiberg.