Strings and D-branes in holographic backgrounds

TL;DR

This paper reviews recent advances in non-rational conformal field theories and their role in modeling exact holographic backgrounds in superstring theory, focusing on the SL(2,R)/U(1) coset and related D-brane boundary states.

Contribution

It provides a comprehensive analysis of the modular properties, partition functions, and boundary states of these theories, extending to NS5-brane backgrounds and Little String Theories.

Findings

Characterized the modular properties of the theories.

Constructed exact boundary states for D-branes.

Applied results to NS5-brane backgrounds and Little String Theories.

Abstract

We review recent progress in the study of non-rational (boundary) conformal field theories and their applications to describe exact holographic backgrounds in superstring theory. We focus mainly on the example of the supersymmetric coset SL(2,R)/U(1), corresponding to the two-dimensional black hole, and its dual N=2 Liouville. In particular we discuss the modular properties of their characters, their partition function as well as the exact boundary states for their various D-branes. Then these results are used to construct the corresponding quantities in the CFT of the NS5-brane background, with applications to Little String Theories.