On Classification of QCD defects via holography

TL;DR

This paper classifies various defects in holographic models of QCD, revealing how their stability and tension change across phase transitions and how this affects the theta dependence of the partition function.

Contribution

It provides a systematic classification of defects in holographic QCD models and analyzes their stability and tension behavior across phase transitions.

Findings

Stable objects become tensionless in the other phase.

Theta dependence of the partition function changes drastically at the phase transition.

Defect stability correlates with phase transition properties.

Abstract

We discuss classification of defects of various codimensions within a holographic model of pure Yang-Mills theories or gauge theories with fundamental matter. We focus on their role below and above the phase transition point as well as their weights in the partition function. The general result is that objects which are stable and heavy in one phase are becoming very light (tensionless) in the other phase. We argue that the $\theta$ dependence of the partition function drastically changes at the phase transition point, and therefore it correlates with stability properties of configurations. Some possible applications for study the QCD vacuum properties above and below phase transition are also discussed.