Aspects of AdS$_2$ Quantum Gravity and the Karch-Randall Braneworld

TL;DR

This paper explores quantum gravity in AdS$_2$ using the Karch-Randall braneworld, revealing emergent dilaton gravity models and their holographic duals, with implications for understanding quantum gravity and a discussion of spectral puzzles.

Contribution

It introduces a class of dilaton gravity models derived from Karch-Randall branes, connecting them to holographic duals and addressing spectral puzzles in AdS$_2$ quantum gravity.

Findings

Emergence of dilaton gravity models from brane tensions

JT gravity as a special case of the models

Holographic duals as one-dimensional quantum mechanics

Abstract

In this paper, we use the Karch-Randall braneworld to study theories of quantum gravity in two dimensional (nearly) anti-de Sitter space (AdS$_2$). We focus on effective gravitational theories in the setup with two Karch-Randall branes embedded in an asymptotically AdS$_3$ bulk forming a wedge. We find the appearance of two-dimensional Einstein-Hilbert gravity (or the Lorenzian version of Marolf-Maxfield theory) when the branes are rigid but the emergence of a class of dilaton gravity models parameterized by the tensions of the two branes when brane fluctuations are accounted for. A special case of our result is Jackiw-Teitelboim (JT) gravity, which has been proven useful to address many important problems in quantum gravity. An important implication of our work is that these models have holographic duals as one-dimensional quantum mechanics systems. At the end, we discuss a puzzle regarding the energy spectrum and its resolution.