Cosmic String Current Stability

TL;DR

This paper investigates the stability and properties of fermionic currents on cosmic strings, analyzing their spectrum, interactions, and conditions for survival across phase transitions.

Contribution

It provides a detailed analysis of fermionic charge carrier stability, spectrum, and interactions on cosmic strings, including effects of electroweak symmetry breaking.

Findings

Neutral fermion currents are always chiral or time-like.

Zero modes can survive electroweak phase transition if isolated from the plasma.

Current-current scattering is negligible at low string densities.

Abstract

The stability of fermionic charge carriers on cosmic strings is considered. We show that neutral fermion currents in cosmic strings are always chiral or time-like, in contrast to the case of bosonic currents. The spectrum of bound states on an abelian SO(10) string is determined both before and after the electroweak phase transition. We determine the mass acquired by the zero mode at this transition. A range of charge carrier scattering processes are considered and corresponding decay rates calculated. Couplings between the carriers and the electroweak sector generate scattering from the plasma which can thermalise some currents. If the zero mode is isolated from the electroweak sector, then it survives. Current-current scattering is considered, but found to be unimportant in realistic settings where the string density is low.