Nonabelian Strings and Axion

TL;DR

This paper explores how axions influence confinement and deconfinement phenomena in two-dimensional models and four-dimensional Yang-Mills theory, revealing that axions can cause deconfinement in some cases but not others, and identifying axion radiation effects.

Contribution

It demonstrates that axions induce deconfinement in 2D CP(N-1) models but do not do so for monopoles in 4D Yang-Mills, and uncovers axion radiation from monopole pairs on non-Abelian strings.

Findings

Axions cause deconfinement in 2D CP(N-1) models.

Bulk axions do not deconfine monopoles in 4D Yang-Mills.

Axion radiation is emitted by monopole-antimonopole pairs on strings.

Abstract

We address two distinct but related issues: (i) the impact of (two-dimensional) axions in a two-dimensional theory known to model confinement, the CP(N-1) model; (ii) bulk axions in four-dimensional Yang-Mills theory supporting non-Abelian strings. In the first case n, \bar n kinks play the role of "quarks." They are known to be confined. We show that introduction of axions leads to deconfinement (at very large distances). This is akin to the phenomenon of wall liberation in four-dimensional Yang-Mills theory. In the second case we demonstrate that the bulk axion does not liberate confined (anti)monopoles, in contradistinction with the two-dimensional model. A novel physical effect which we observe is the axion radiation caused by monopole-antimonopole pairs attached to the non-Abelian strings.