Runaway dilatonic domain walls

TL;DR

This paper investigates the stability of domain walls in theories with extra dimensions, revealing how energy densities can destabilize compactifications and lead to singularities or decompactification, with implications for cosmology.

Contribution

It provides analytical and numerical analysis of domain wall stability in extra-dimensional theories, connecting instabilities to vacuum transitions and cosmological phenomena.

Findings

Energy density inside walls can destabilize volume moduli.

Instabilities can produce singularities or decompactification regions.

Implications for topological defect networks and eternal inflation.

Abstract

We explore the stability of domain wall and bubble solutions in theories with compact extra dimensions. The energy density stored inside of the wall can destabilize the volume modulus of a compactification, leading to solutions containing either a timelike singularity or a region where space decompactifies, depending on the metric ansatz. We determine the structure of such solutions both analytically and using numerical simulations, and analyze how they arise in compactifications of Einstein--Maxwell theory and Type IIB string theory. The existence of instabilities has important implications for the formation of networks of topological defects and the population of vacua during eternal inflation.