Enhanced asymptotic symmetry algebra of AdS3

TL;DR

This paper generalizes boundary conditions in 3D AdS gravity, revealing an enhanced asymptotic symmetry algebra with additional degrees of freedom and a richer structure of central charges.

Contribution

It introduces a new class of boundary conditions leading to an expanded asymptotic symmetry algebra with three central charges.

Findings

Enhanced symmetry algebra with additional U(1) current algebra.

Presence of a new central charge in the surface charge algebra.

Extension of Brown-Henneaux boundary conditions.

Abstract

A generalization of the Brown-Henneaux boundary conditions is introduced for pure gravity with negative cosmological constant in 3 dimensions. This leads to new degrees of freedom and to an enhancement of the symmetry algebra. Up to the zero modes, it consists of two copies of the semi-direct product of a Virasoro algebra with a U(1) current algebra. The associated surface charge algebra now contains three non-zero central charges: the two usual Brown-Henneaux central charges and one new quantity.