Some comments about emission channels of non abelian vortices

TL;DR

This paper investigates how non-Abelian properties of vortices in an SU(2) gauge model influence their emission characteristics, especially gravitational and axion emissions, revealing that non-Abelianity affects gravitational loop factors but not axion emission significantly.

Contribution

It introduces a method to identify non-Abelian vortices through their physical effects, analyzing emission channels and deviations in gravitational loop factors in a simple SU(2) model.

Findings

Non-Abelian vortices show deviations in gravitational loop factors.

Axion emission is relatively insensitive to non-Abelianity.

No vortex point reaches the speed of light when modes are excited.

Abstract

As is well established, several gauge theories admit vortices whose mean life time is very large. In some cases, this stability is a consequence of the topology of the symmetry group of the underlying theory. The main focus of the present work is, given a putative vortex, to determine if it is non abelian or not by analysis of its physical effects. The example considered here is the simplest one namely, a $SU(2)$ gauge model whose internal orientational space is described by $S^2$. Axion and gravitational emission are mainly considered. It is found that the non abelian property is basically reflected in a deviation of gravitational loop factor $\gamma_l$ found in \cite{vachaspati}-\cite{burden}. The axion emission instead, is not very sensitive to non abelianity, at least for this simple model. Another important discrepancy is that no point of the vortex reaches the speed of light when orientational modes are excited. In addition, the total power corresponding to each of these channels is compared, thus adapting the results of \cite{davis}-\cite{peloso} to the non abelian context. The excitations considered here are simple generalizations of rotating or spike string ansatz known in the literature \cite{ruso1}-\cite{kruczenski}. It is suggested however, that for certain type of semi-local strings whose internal moduli space is non compact, deviations due to non abelianity may be more pronounced.