QCD Kondo excitons

TL;DR

This paper theoretically predicts the existence of neutral bound states called QCD Kondo excitons, formed by light and heavy quarks in high-density quark matter, revealing new quasiparticles and transport phenomena.

Contribution

The paper introduces the concept of QCD Kondo excitons as a novel type of quasiparticle in quark matter, extending the analogy of the Kondo effect from condensed matter to QCD.

Findings

Existence of neutral QCD Kondo excitons with various quantum numbers.

QCD Kondo excitons influence neutral currents in transport phenomena.

Potential for detection via lattice QCD simulations.

Abstract

The quantum chromodynamics (QCD) Kondo effect is a quantum phenomenon in which heavy quarks ($c$, $b$) exist as impurity particles in quark matter composed of light quarks ($u$, $d$, $s$) at extremely high density. This is analogous to the famous Kondo effect in condensed matter physics. In the present paper, we show theoretically the existence of the "QCD Kondo excitons", i.e., the bound states of light quarks and heavy quarks, as the lowest-excitation modes above the ground state of the quark matter governed by the QCD Kondo effect. These are neutral for color and electric charges, similarly to the Kondo excitons in condensed matter, and they are new type of quasiparticles absent in the normal phase of quark matter. The QCD Kondo excitons have various masses and quantum numbers, i.e., flavors and spin parities (scalar, pseudoscalar, vector, and axialvector). The QCD Kondo excitons lead to the emergence of the neutral currents in transport phenomena, which are measurable in lattice QCD simulations. The study of the QCD Kondo excitons will provide us with understanding of new universal properties shared by quark matter and condensed matter.