Competing color superconductivity and color Kondo effect in quark matter

TL;DR

This paper explores the complex interplay between color superconductivity and the color Kondo effect in dense quark matter, revealing new phases and boundary phenomena through an exactly solvable model.

Contribution

It introduces a toy model that captures the competition between bulk color superconductivity and impurity screening, uncovering a novel intermediate phase with unique impurity behavior.

Findings

Identification of regimes with either Kondo screening or unscreened moments

Discovery of an intermediate phase with a single-particle bound state within the gap

Application of Bethe Ansatz to elucidate boundary physics in quark matter

Abstract

The competition between bulk color superconductivity and the localized screening of a heavy quark impurity, analogous to the Kondo effect, leads to a rich spectrum of phenomena in dense quark matter. We investigate this competition at the edge of a superconducting quark bulk, where both the superconducting gap and the Kondo scale are dynamically generated in a tractable toy model. Utilizing the exact Bethe Ansatz method, we elucidate the resulting boundary physics. We identify distinct regimes characterized by either multi-particle Kondo screening or an unscreened local moment. Crucially, we also uncover a novel intermediate phase featuring impurity screening through a single-particle bound state formed within the superconducting gap. The toy model presented in this work highlights the complex interplay between dynamically generated bulk properties and boundary impurities in extreme QCD environments, offering potential insights into phenomena occurring in heavy-ion collisions and compact stars.