Kosterlitz-Thouless transition on the worldsheet of the QCD string

TL;DR

This paper studies the QCD string's behavior in a periodic transverse space, predicting a Kosterlitz-Thouless transition on the worldsheet that affects the flux-tube energy spectrum and effective central charge.

Contribution

It introduces a generalized effective string action and predicts a vortex-driven Kosterlitz-Thouless transition in the QCD string's worldsheet theory.

Findings

Prediction of a Kosterlitz-Thouless transition driven by vortices.

Development of a mass gap in the periodic component of the worldsheet displacement.

Drop of the effective central charge by one unit at the transition.

Abstract

We investigate the properties of the QCD string in the Euclidean SU(N) pure gauge theory when the space-time dimensions transverse to it are periodic. We propose a generalisation of the Luscher-Weisz effective string action for the flux-tube energy levels at finite L_perp. As the size of one transverse dimension is varied, we predict a Kosterlitz-Thouless transition of the worldsheet field theory driven by vortices, after which the periodic component of the worldsheet displacement vector develops a mass gap and the effective central charge drops by one unit. The universal properties of the transition are emphasized.