D-brane Black Holes: Large-N Limit and the Effective String Description

TL;DR

This paper derives the effective conformal field theory description of 5D D-brane black holes from gauge theory, showing how large charge limits lead to a superconformal field theory with specific properties.

Contribution

It provides a derivation of the effective N=4 superconformal field theory for D1-D5 black holes from gauge theory, including the effects of finite charges and marginal perturbations.

Findings

Effective CFT with c=6 describes low-energy excitations.

Large charge limit justifies the derivation beyond weak coupling.

Identification of marginal perturbation for finite Q_5.

Abstract

We address the derivation of the effective conformal field theory description of the 5-dimensional black hole, modelled by a collection of D1- and D5- branes, from the corresponding low energy U(Q_1)xU(Q_5) gauge theory. Finite horizon size at weak coupling requires both Q_1 and Q_5 to be large. We derive the result in the moduli space approximation (say for Q_1>Q_5) and appeal to supersymmetry to argue its validity beyond weak coupling. As a result of a combination of quenched Z_{Q_1} Wilson lines and a residual Weyl symmetry, the low-lying excitations of the U(Q_1)xU(Q_5) gauge theory are described by an effective N=4 superconformal field theory with c=6 in 1+1 dimensions, where the space is a circle of radius RQ_1Q_5. We also discuss the appearance of a marginal perturbation of the effective conformal field theory for large but finite values of Q_5.