Worldsheet description of black hole solutions in string theory

The goal of the thesis is to investigate exact worldsheet descriptions of some black hole solutions in string theory and to analyse their properties. In particular, recently a worldsheet description has been found for a class of microstate solutions (describing some of the microstates of the black hole) in terms of null-gauged Wess-Zumino-Witten (WZW) models. In such cases, the consistency of the worldsheet theory imposes the absence of horizons, as expected from a solution describing a particular microstate. The thesis will explore more general worldsheet models of this kind with the aim of understanding whether they can describe string dynamics on black hole solutions, and to study their properties. First, we will focus on a worldsheet description of Witten’s two-dimensional black hole in both Euclidean and Lorentzian signatures, and we will show that such solutions can be obtained in the null-gauging formalism. This investigation is then extended to a more general class of models that describe non-extremal three-charge black holes. The spectrum of such models will be studied.