Entropy and replica geometry in generic two-dimensional dilaton gravity theories

TL;DR

This paper explores entropy and replica geometries in a novel two-dimensional dilaton gravity model, addressing the black hole information paradox and proposing new saddle points in the gravitational path integral.

Contribution

It introduces a new model of black hole entropy in 2D dilaton gravity with non-trivial bulk action and constructs replica wormhole geometries without holography.

Findings

Resolved Hawking's entropy paradox with new saddle points.

Constructed replica wormhole geometries explicitly.

Identified differences from JT gravity models.

Abstract

We set up a new version of black hole information paradox in an eternal Narayan black hole, a generic two-dimensional dilaton gravity theory with non-trivial on-shell bulk action and a product of dimensional reduction from higher-dimensional AdS black brane, joined to Minkowski bath on both sides. We also report both similarities as well as important differences between our model and the famous model of JT gravity coupled with baths. The contradiction of Hawking's result of entanglement entropy with unitarity is resolved by including a new saddle in the Euclidean gravitational path integral. As part of ongoing and developing research, we attempt, and have had partial success, to explicitly construct the replica wormhole geometry for our model to fully justify the quantum extremal surface calculations with Euclidean gravitational path integral, without using holography.