Asymptotic symmetries from the string worldsheet

TL;DR

This paper derives asymptotic symmetries in string theory on AdS3 backgrounds directly from worldsheet equations, providing a new approach that bypasses supergravity analysis and applies to flat spacetime as well.

Contribution

It introduces a method to obtain asymptotic symmetries from the worldsheet perspective, including explicit derivation of Brown-Henneaux and BMS3 generators.

Findings

Derived Brown-Henneaux vectors from worldsheet constraints.

Obtained BMS3 generators in flat spacetime from the worldsheet.

Provided a framework to study asymptotic symmetries without supergravity.

Abstract

In IIB string theory on AdS$_3$ background with NS-NS fluxes, we show that Brown-Henneaux asymptotic Killing vectors can be derived by requiring both the worldsheet equations of motion and Virasoro constraints are preserved near the asymptotic boundary of the target spacetime. The charges on the worldsheet that generate the corresponding transformations can be written down in both the Lagrangian formalism and Hamiltonian formalism. This provides a method of studying asymptotic symmetry of the target spacetime directly from worldsheet string theories, without using results from the supergravity limit. As an example, we apply this method to flat spacetime in three dimensions and obtain the BMS$_3$ generators on the worldsheet theory.