Abstract

The quantization of pure 3D gravity with Dirichlet boundary conditions on a finite boundary is of interest both as a model of quantum gravity in which one can compute quantities which are ``more local" than S-matrices or asymptotic boundary correlators, and for its proposed holographic duality to T\overline{T}TT¯-deformed CFTs. In this work we apply covariant phase space methods to deduce the Poisson bracket algebra of boundary observables. The result is a one-parameter nonlinear deformation of the usual Virasoro algebra of asymptotically AdS_33 gravity. This algebra should be obeyed by the stress tensor in any T\overline{T}TT¯-deformed holographic CFT. We next initiate quantization of this system within the general framework of coadjoint orbits, obtaining — in perturbation theory — a deformed version of the Alekseev-Shatashvili symplectic form and its associated geometric action. The resulting energy spectrum is consistent with the expected spectrum of T\overline{T}TT¯-deformed theories, although we only carry out the explicit comparison to \mathcal{O}(1/\sqrt{c})𝒪(1/c) in the 1/c1/c expansion.

Highlights

  • We consider the space of metrics with fixed topology while demanding that the metric on the boundary is ds2

  • We first compute the Poisson bracket algebra of observables by putting the classical theory in canonical form. This involves characterizing the general classical solution and writing down a candidate symplectic form on this space. To render this form non-degenerate, we need to identifying appropriate gauge orbits, each of which defines a point in covariant phase space

  • We discuss the gravitational symplectic form and find that large diffeomorphisms are generated by charges that can be written in terms of the stress tensor on the spatial boundary

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Summary

Introduction

Within the framework of our current understanding of quantum gravity, the only observables with a mathematically precise definition involve asymptotic quantities, such as the S-matrix in Minkowski space or boundary correlators in (A)dS. In the asymptotically AdS case Brown and Henneaux demonstrated the emergence of the Virasoro algebras present in the CFT; how are these algebras deformed if we impose Dirichlet boundary conditions at finite ρc?4. Another goal is to gain a better understanding of observables that probe the UV structure of T T -deformed theories; there are reasons to expect At the level of classical pure gravity these two descriptions are equivalent, as adding the T T deformation can be shown to coincide with subtracting the bulk action associated with the spacetime region between the cutoff and the asymptotic boundary [53]. In the present work we focus on the Dirichlet cutoff picture

Summary and results
Canonical formulation
Covariant phase space
Gravity with Dirichlet boundary conditions
Gravity with a boundary
Symplectic form and boundary charges
Pure AdS3 gravity and its connection to the T T deformation
Warmup
Asymptotic symmetry algebra of AdS3
The Alekseev-Shatashvili symplectic form
Perturbative expansion
Metrics obeying Dirichlet boundary condition
Quantization
Discussion
Full Text
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