# Asymptotic Symmetries of Three-Dimensional Black Strings

## TL;DR

This paper establishes a consistent phase space for 3D black strings within heterotic string theory, revealing an asymptotic symmetry algebra combining a Virasoro algebra with three U(1) symmetries.

## Contribution

It introduces boundary conditions for 3D black strings in heterotic string theory and uncovers their asymptotic symmetry algebra and thermodynamic properties.

## Key findings

- Asymptotic symmetry algebra includes a Virasoro and three U(1) generators.
- Boundary conditions are consistent with the low energy heterotic string effective action.
- Zero-mode solutions exhibit unique thermodynamic features.

## Abstract

We determine a consistent phase space for a theory consisting in the Einstein-Hilbert action coupled to matter fields (dilaton, one-form, two-form) and containing three-dimensional black strings (the Horne-Horowitz solution and generalizations thereof). The theory at hand is the low energy effective action for the bosonic sector of heterotic string theory. We find a consistent set of boundary conditions whose algebra of asymptotic charges consist in a single Virasoro algebra supplemented by three global $u(1)$ generators. We also discuss the thermodynamics of the zero-mode solutions and point out some peculiar features of this system.