# String Theory of Supertubes

## TL;DR

This paper explores the string theory description of supertubes in AdS3 backgrounds, revealing stringy structures near fivebranes and their implications for black hole entropy via holography.

## Contribution

It introduces a string theory framework for supertubes using null-gauged WZW models, uncovering stringy effects near fivebranes and their role in holographic RG flows.

## Key findings

- Stringy winding operators resolve fivebrane near-source structure.
- Null-gauged WZW models describe holographic RG flows to AdS3.
- Long strings in D-brane sector relate to black hole entropy.

## Abstract

String theory on AdS3 backgrounds arises as an IR limit of Little String Theory on NS5-branes. A wide variety of holographic RG flows from the fivebrane theory in the UV to (orbifolds of) AdS3 in the IR is amenable to exact treatment in worldsheet string theory as a class of null-gauged WZW models. The condensate of stringy winding operators which resolves the near-source structure of fivebranes on the Coulomb branch plays a crucial role in AdS3, revealing stringy structure invisible to the supergravity approximation. The D-brane sector contains precursors of the long strings which dominate black hole entropy in the dual spacetime CFT.