Stability of Sigma-Model Strings and Textures

TL;DR

This paper investigates the stability of sigma-model strings and textures in flat spacetime and during cosmological expansion, finding that expansion stabilizes strings but not textures against decay.

Contribution

It introduces a generalized stability concept showing that cosmological expansion stabilizes sigma-model strings, while textures remain unstable.

Findings

Strings are stabilized by current cosmological expansion.

Textures remain unstable despite expansion.

Expansion affects stability differently for strings and textures.

Abstract

In flat space-time, sigma-model strings and textures are both unstable to collapse and subsequent decay. With sufficient cosmological expansion, however, they are stable in a generalized sense: a small perturbation will cause them to change their shape, but they do not decay. The current rate of expansion is sufficient to stabilize strings, but not textures.