Black holes in string theory: Beyond supergravity.

Abstract

The aim of this thesis is to demonstrate the effectiveness of worldsheet string theory in the context of black hole physics, going beyond the supergravity approximation. For a certain class of microstates, which in a particular limit admit an α′-exact description in terms of gauged Wess-Zumino-Witten (gWZW) models, we will derive consistency conditions, spectrum of massless excitations, and compute an extensive set of correlation functions. In particular, we will show how the consistency of the worldsheet conformal field theory (CFT) is in one-to-one correspondence with the absence of closed timelike curves, singularities, and horizon of the background. These conditions give rise to a set of quantisation constraints on the gauging parameters that will allow us to prove that the family of microstates we consider is the most general solution of our gWZW model. In addition, we will construct the physical states in the full gauged model and in its three-dimensional anti-de Sitter (AdS3) limit. We will also derive a formula that expresses heavy-light correlators involving an arbitrary number of massless fields in the AdS3 limit of the coset model in terms of AdS3×S3 vacuum correlator. Finally, we prove a conjecture on three-point functions in the SL(2,R) WZW model involving spectrally flowed vertex operators. These results constitute an important contribution for the understanding of black hole microstates beyond the usual supergravity approximation, and for AdS3/CFT2 holography at finite ’t Hooft coupling.<br/