Kondo phase diagram of quark matter

Abstract

We find a novel type of phase, “the Kondo phase,” in a quark matter containing heavy quarks as impurities. This phase allows the QCD Kondo effect to occur between a light quark (ψ) and a heavy quark (Ψ), and is characterized by a nonzero heavy-light condensate 〈ψ¯Ψ〉 which measures the strength of mixing between ψ and Ψ and represents formation of the Kondo cloud, the ground state composed of light and heavy quarks. Within a field-theoretic approach and mean-field approximation, we obtain the gap equation which self-consistently and non-perturbatively determines the gap Δ∼〈ψ¯Ψ〉. By solving the gap equation with the condition for the heavy-quark number conservation, we draw a phase diagram in μ (the light-quark chemical potential) and λ (an analog of the heavy-quark chemical potential) plane, and identify the density region of the Kondo phase.