Instability of colliding metastable strings

TL;DR

This paper investigates the stability of colliding metastable cosmic strings called R-tubes, revealing how their interactions can lead to instability and vacuum transition, which constrains supersymmetry breaking models.

Contribution

It provides the first field-theoretic simulation study of the dynamical stability of colliding metastable strings in SUSY models.

Findings

Strings become unstable depending on collision angle and speed.

False vacuum is replaced by true vacuum after collision.

Rapid expansion of strings or bubble formation causes instability.

Abstract

The breaking of $U(1)_R$ symmetry plays a crucial role in modeling the breaking of supersymmetry (SUSY). In the models that possess both SUSY preserving and SUSY breaking vacua, tube-like cosmic strings called R-tubes, whose surfaces are constituted by domain walls interpolating a false and a true vacuum with some winding numbers, can exist. Their (in)stability can strongly constrain SUSY breaking models theirselves. In the present study, we investigate the dynamical (in)stability of two colliding metastable tube-like strings by field-theoretic simulations. From them, we find that the strings become unstable, depending on the relative collision angle and speed of two strings, and the false vacuum is eventually filled out by the true vacuum owing to rapid expansion of the strings or unstable bubbles created as remnants of the collision.