Signature change in 2-dimensional black-hole models of loop quantum gravity

TL;DR

This paper explores how loop quantum gravity induces signature change in 2D black-hole models, extending previous spherically symmetric results to dilaton models and analyzing the challenges in coupling matter and operator ordering.

Contribution

It extends the understanding of signature change due to holonomy modifications to 2D dilaton models and different canonical variables, including the CGHS solution.

Findings

Signature change occurs in 2D dilaton models of loop quantum gravity.

Obstructions are identified in coupling matter and operator ordering for anomaly-free models.

The results generalize previous spherically symmetric findings to broader 2D models.

Abstract

Signature change has been identified as a generic consequence of holonomy modifications in spherically symmetric models of loop quantum gravity with real connections, which includes modified Schwarzschild solutions. Here, this result is extended to 2-dimensional dilaton models and to different choices of canonical variables, including in particular the Callan-Giddings-Harvey-Strominger (CGHS) solution. New obstructions are found to coupling matter and to including operator-ordering effects in an anomaly-free manner.