Effective Field Theory for Long Strings

TL;DR

This paper develops a consistent effective field theory for long strings in non-Abelian gauge theories, fixing vortex parameters and deriving an effective string description with a single tension parameter, improving understanding of flux tube structure.

Contribution

It introduces a consistency condition for Z_N vortices that determines the vortex structure parameter and links the effective field theory to an effective string theory with a single parameter.

Findings

Fixes the Landau-Ginzburg parameter for Z_N vortices based on physical consistency.

Provides a physical picture of flux tube pressure distribution differing from Abelian Higgs vortices.

Derives an effective string theory with the Nambu-Goto action from vortex fluctuations.

Abstract

In previous work we used magnetic SU(N) gauge theory with adjoint representation Higgs scalars to describe the long distance quark-antiquark interaction in pure Yang-Mills theory, and later to obtain an effective string theory. The empirically determined parameters of the non-Abelian effective theory yielded $Z_N$ flux tubes resembling those of the Abelian Higgs model with Landau-Ginzburg parameter equal to $ 1/\sqrt{2}$, corresponding to a superconductor on the border between type I and type II. However, the physical significance of the differences between the Abelian and the $Z_N$ vortices was not elucidated and no principle was found to fix the value of the 'Landau-Ginzburg parameter' $\kappa$ of the non-Abelian theory determining the structure of the $Z_N$ vortices. Here we reexamine this point of view. We propose a consistency condition on $Z_N$ vortices underlying a confining string. This fixes the value of $\kappa$. The transverse distribution of pressure $p(r)$ in the resulting $Z_N$ flux tubes provides a physical picture of these vortices which differs essentially from that of the vortices of the Abelian Higgs model. We speculate that this general picture is valid independent of the details of the effective magnetic gauge theory from which it was obtained. Long wavelength fluctuations of the axis of the $Z_N$ vortices lead from an effective field theory to an effective string theory with the Nambu-Goto action. This effective string theory depends on a single parameter, the string tension $\sigma$. In contrast, the effective field theory has a second parameter, the intrinsic width 1/M of the flux tube.