From black holes to baby universes in CGHS gravity

TL;DR

This paper introduces a variant of CGHS gravity that models near horizon black hole perturbations, is dual to a Gaussian ensemble, and offers insights into baby universes, factorization, and non-perturbative completions.

Contribution

It presents a new flat space analog of JT gravity, computes exact quantities, and explores non-perturbative matrix model completions.

Findings

Duality to a Gaussian ensemble established

Exact calculations of free energy performed

Evidence for non-perturbative matrix model provided

Abstract

We study $\widehat{\text{CGHS}}$ gravity, a variant of the matterless Callan-Giddings-Harvey-Strominger model. We show that it describes a universal sector of the near horizon perturbations of non-extremal black holes in higher dimensions. In many respects this theory can be viewed as a flat space analog of Jackiw-Teitelboim gravity. The result for the Euclidean path integral implies that $\widehat{\text{CGHS}}$ is dual to a Gaussian ensemble that we describe in detail. The simplicity of this theory allows us to compute exact quantities such as the quenched free energy and provides a useful playground to study baby universes, averages and factorization. We also give evidence for the existence of a non-perturbative completion in terms of a matrix model. Finally, flat wormhole solutions are discussed.