Bra-ket wormholes and Casimir entropy

TL;DR

This paper investigates how gauge symmetries and boundary condition integrations influence the stability and phase structure of bra-ket wormholes in Euclidean gravity, emphasizing the role of Casimir entropy in large gauge groups.

Contribution

It introduces the concept of Casimir entropy as a measure over boundary conditions and analyzes its impact on bra-ket wormhole actions for non-Abelian gauge groups.

Findings

Casimir entropy significantly affects wormhole phase diagrams for large gauge groups.

No violations of strong subadditivity are observed in the studied setup.

Boundary condition integration alters the wormhole stability and phase structure.

Abstract

Bra-ket wormholes are non-trivial saddles in Euclidean gravity. They have to be sustained by negative Casimir energy of matter fields inside the throat. However, Casimir energy is very sensitive to boundary conditions and in presence of gauge symmetries one has to integrate over all possible boundary conditions for the matter fields, as they are a part of bra-ket wormhole moduli. For non- Abelian gauge groups the corresponding measure for the boundary conditions, which we call Casimir entropy, is non-trivial and it competes with the Casimir energy. We find that for large gauge groups this significantly affects the bra-ket wormhole action and modifies the phase diagram. Despite that, we do not find any violations of strong subadditivity in the setup proposed by Chen, Gorbenko and Maldacena.