Non-Abelian Strings in High Density QCD: Zero Modes and Interactions

TL;DR

This paper investigates non-Abelian semi-superfluid strings in high density QCD, revealing their zero modes, interactions, and implications for the stability of color superconductors under external gauge fields.

Contribution

It demonstrates the existence of normalizable orientational zero modes and derives the universal repulsive interaction among these strings, showing their stability and decay properties.

Findings

Non-Abelian strings possess normalizable orientational zero modes.

Parallel strings exhibit universal repulsive interactions.

Color superconductors remain stable under external color gauge fields.

Abstract

The most fundamental strings in high density color superconductivity are the non-Abelian semi-superfluid strings which have color gauge flux tube but behave as superfluid vortices in the energetic point of view. We show that in addition to the usual translational zero modes, these vortices have normalizable orientational zero modes in the internal space, associated with the color-flavor locking symmetry broken in the presence of the strings. The interaction among two parallel non-Abelian semi-superfluid strings is derived for general relative orientational zero modes to show the universal repulsion. This implies that the previously known superfluid vortices, formed by spontaneously broken U(1)_B, are unstable to decay. Moreover, our result proves the stability of color superconductors in the presence of external color gauge fields.