Gapless Color Superconductivity

TL;DR

This paper explores the theoretical possibility of gapless color superconductivity in high-density QCD, showing that certain condensates can lead to a gapless quasiparticle spectrum, which may be metastable.

Contribution

It introduces the concept of gapless color superconductivity and analyzes its conditions within a simplified model, highlighting its potential metastability.

Findings

Gapless quasiparticle spectrum can occur in color superconductors.

Such phases may exhibit a Meissner effect without an energy gap.

Gapless phase might be metastable rather than stable.

Abstract

We present the dispersion relations for quasiparticle excitations about the color-flavor locked ground state of QCD at high baryon density. In the presence of condensates which pair light and strange quarks there need not be an energy gap in the quasiparticle spectrum. This raises the possibility of gapless color superconductivity, with a Meissner effect but no minimum excitation energy. Analysis within a toy model suggests that gapless color superconductivity may occur only as a metastable phase.