QCD Kondo excitons

Abstract

The QCD Kondo effect is a quantum phenomenon when the heavy quarks (c, b) exist as impurity particles in quark matter composed of the light quarks (u, d, s) at extremely high density. This is analogous to the famous Kondo effect in condensed matter physics. In the present study, 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. Those are neutral for color and electric charges, similarly to the Kondo excitons in condensed matter, and they are new type of quasi-particles absent in the normal phase of the 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 new universal properties shared by the quark matter and the condensed matter. arXiv:1909.07573v1 [nucl-th]

Kondo effect with Wilson fermions

“…Such "relativistic" Kondo effects can occur in relativistic-fermion systems including impurities, such as graphene (see Ref. [6] for a review), Dirac/Weyl semimetals [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23], dense nuclear matter [24][25][26][27], and dense quark matter [13,24,[28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44]. Among them, the QCD Kondo effect [24,28] is induced by the color exchange interaction between a light quark and an impurity quark, which is based on quantum chromodynamics (QCD).…”

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

“…In fact, it was shown that the Kondo effect arises in nuclear matter when Σ c and Σ * c baryons or D and D * mesons exist as impurities, where the spin and/or isospin exchange serves as the non-Abelian interaction [3,[5][6][7]. In addition, many works on Kondo effect in a relativistic system have been done in the literatures [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. In this way, the interdisciplinary study bridging condensedmatter physics and QCD/hadron physics focused on the Kondo effect is attracting attention.…”

Chiral separation effect catalyzed by heavy impurities

“…2 While the Kondo effect was originally found in metal including impurities in the context of condensed-matter physics [13][14][15][16][17], it has been theoretically shown to emerge in quark matter [18,19] (See Refs. [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] for related discussions). 3 The Kondo effect is known to change the transport phenomena characteristically.…”