Stability of Axion-Dilaton Wormholes

TL;DR

This paper investigates the stability of Euclidean axion-dilaton wormholes, finding that massless solutions are always stable and certain massive solutions are stable depending on parameters, highlighting ongoing puzzles in wormhole physics.

Contribution

It provides a detailed analysis of the perturbative stability of axion-dilaton wormholes with both massless and massive dilatons, identifying conditions for stability and instability.

Findings

Massless wormholes are always perturbatively stable.

Stable solutions with massive dilaton depend on dilaton potential, coupling, and axion charge.

Solutions from bifurcation points have unstable branches with negative modes.

Abstract

We study the perturbative stability of Euclidean axion-dilaton wormholes that asymptotically approach flat space, both with a massless and a massive dilaton, and focussing on homogeneous perturbations. We find massless wormholes to always be perturbatively stable. The phenomenologically more relevant case of a massive dilaton presents us with a wide variety of wormhole solutions, depending on the dilaton coupling and mass, and on the axion charge. We find that the solutions with the smallest dilaton potential are perturbatively stable and dominant, even in cases where the wormhole solutions are not continuously connected to the massless case by decreasing the mass. For branches of solutions emanating from a bifurcation point, one side of the branch always contains a negative mode in its spectrum, rendering such solutions unstable. The existence of classes of perturbatively stable wormhole solutions with massive dilaton sharpens the puzzles associated with Euclidean wormholes.