# JT Gravity and the Ensembles of Random Matrix Theory

## TL;DR

This paper extends the correspondence between Jackiw-Teitelboim (JT) gravity and random matrix ensembles to include cases with time-reversal symmetry, fermions, and supersymmetry, connecting various boundary symmetries with specific matrix ensembles.

## Contribution

It generalizes the JT gravity-matrix ensemble correspondence to all ten standard ensembles, including those with time-reversal symmetry, fermions, and supersymmetry, and extends Mirzakhani's recursion to super Riemann surfaces.

## Key findings

- JT gravity relates to all ten random matrix ensembles.
- Inclusion of unorientable spacetimes requires Reidemeister-Ray-Singer torsion.
- Supersymmetric cases involve volumes of super Riemann surfaces.

## Abstract

We generalize the recently discovered relationship between JT gravity and double-scaled random matrix theory to the case that the boundary theory may have time-reversal symmetry and may have fermions with or without supersymmetry. The matching between variants of JT gravity and matrix ensembles depends on the assumed symmetries. Time-reversal symmetry in the boundary theory means that unorientable spacetimes must be considered in the bulk. In such a case, the partition function of JT gravity is still related to the volume of the moduli space of conformal structures, but this volume has a quantum correction and has to be computed using Reidemeister-Ray-Singer "torsion." Presence of fermions in the boundary theory (and thus a symmetry $(-1)^F$) means that the bulk has a spin or pin structure. Supersymmetry in the boundary means that the bulk theory is associated to JT supergravity and is related to the volume of the moduli space of super Riemann surfaces rather than of ordinary Riemann surfaces. In all cases we match JT gravity or supergravity with an appropriate random matrix ensemble. All ten standard random matrix ensembles make an appearance -- the three Dyson ensembles and the seven Altland-Zirnbauer ensembles. To facilitate the analysis, we extend to the other ensembles techniques that are most familiar in the case of the original Wigner-Dyson ensemble of hermitian matrices. We also generalize Mirzakhani's recursion for the volumes of ordinary moduli space to the case of super Riemann surfaces.