Heavy-quark spin polarization induced by the Kondo effect in a magnetic field

Kondo cloud of single heavy quark in cold and dense matter

The Kondo effect is a universal phenomena observed in a variety of fermion systems containing a heavy impurity particle whose interaction is governed by the non-Abelian interaction. At extremely high density, I study the Kondo effect by color exchange in quark matter containing a single heavy (charm or bottom) quark as an impurity particle. To obtain the ground state with the Kondo effect, I introduce the condensate mixing the light quark and the heavy quark (Kondo cloud) in the mean-field approximation. I estimate the energy gain by formation of the Kondo cloud, and present that the Kondo clo…

手征对称性破缺相中单重夸克的QCD近藤效应

QCD Kondo effect for single heavy quark in chiral-symmetry broken phase

本文研究手征对称性破缺夸克物质中单重夸克的QCD近藤效应，通过平均场近似计算不同旋量结构的凝聚体能量，发现密度决定凝聚体类型，并用近藤共振解释该转变。

QCD Kondo effect: quark matter with heavy-flavor impurities

We show that the Kondo effect occurs in light quark matter which contains heavy quarks as impurities. We consider a scattering between a heavy-flavor impurity and a light quark near a Fermi surface which is mediated by gluon-exchange interactions. We find that the scattering amplitude has a logarithmic infrared divergence originating from imperfect cancellation between quark-impurity and hole-impurity scatterings in a loop integral, implying the presence of a strongly coupled regime near the Fermi surface. Renormalization group method is used to find the Kondo scale where a running coupling co…

Topology and stability of the Kondo phase in quark matter

We investigate properties of the ground state of a light quark matter with heavy quark impurities. This system exhibits the "QCD Kondo effect" where the interaction strength between a light quark near the Fermi surface and a heavy quark increases with decreasing energy of the light quark towards the Fermi energy, and diverges at some scale near the Fermi energy, called the Kondo scale. Around and below the Kondo scale, we must treat the dynamics nonperturbatively. As a typical nonperturbative method to treat the strong coupling regime, we adopt a mean-field approach where we introduce a conden…

Kondo phase diagram of quark matter

We discuss the ground state of a quark matter containing heavy quarks as impurities in a simple model which exhibits the QCD Kondo effect. The model includes a current-current interaction with the color exchange between a light quark ($ψ$) and a heavy quark ($Ψ$). We introduce a gap function $Δ\sim \langle \bar ψΨ\rangle $ which represents the correlation between $ψ$ and $Ψ$, and perform the mean-field approximation assuming that heavy quarks are uniformly distributed. Values of the gap $Δ$ measure the strength of mixing between $ψ$ and $Ψ$. The gap equation obtained from the minimum of the th…

Two relativistic Kondo effects: Classification with particle and antiparticle impurities

We investigate two different types of relativistic Kondo effects, distinguished by heavy-impurity degrees of freedom, by focusing on the energy-momentum dispersion relations of the ground state with condensates composed of a light Dirac fermion and a nonrelativistic impurity fermion. Heavy fermion degrees of freedom are introduced in terms of two types of heavy-fermion effective theories, in other words, two heavy-fermion limits for the heavy Dirac fermion, which are known as the heavy-quark effective theories (HQETs) in high-energy physics. While the first one includes only the heavy-particle…