Anomalous magnetic moment of hot quarks, inverse magnetic catalysis, and reentrance of the chiral symmetry broken phase

Abstract

The effect of anomalous magnetic moment of quarks on thermodynamic properties of the chiral condensate is studied, using of a two-flavor Nambu-Jona-Lasinio model at finite temperature T , chemical potential µ, and in the presence of a uniform magnetic field eB. To this purpose, the Schwinger linear-in-B ansatz for the quark anomalous magnetic moment in term of the nonperturbative Bohr magneton is considered. In a two-dimensional flavor space, it leads to the correction T Sch =κQeB in the energy dispersion relation of quarks. Here,Q is the quark charge matrix. We consider three different sets forκ, and numerically determine the dependence of the constituent quark mass on T, µ and eB for fixedκ. By exploring the complete phase portrait of this model in T -µ, µ-eB, and T -eB phase spaces for various fixed eB, T , µ andκ, we observe that inverse magnetic catalysis occurs for large enoughκ. Moreover, in the regime of weak magnetic fields, the phenomenon of reentrance of chiral symmetry broken and restored phases occurs for T, µ and eB dependentκ.

Quantum field theory in a magnetic field: From quantum chromodynamics to graphene and Dirac semimetals

“…Taking into account the natural model assumption that the magnetic field scale is much smaller than the ultraviolet cutoff Λ, we conclude that the relation (73) is actually valid in a large window of subcritical couplings, excluding only the nearcritical region.…”

Critical point in the QCD phase diagram for extremely strong background magnetic fields

“…Several attempts have been made recently to understand this behavior in effective approaches to QCD [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33], among others, by introducing new, B-dependent model parameters or by taking into account the running of the QCD coupling with the magnetic field. Several of these models exhibit a non-monotonous T c (B) dependence, with an initial reduction followed by an enhancement due to the magnetic field.…”

Strongly interacting matter under external magnetic fields within nonlocal NJL-type models

“…This effect is known as inverse magnetic catalysis (IMC). Although many scenarios have been considered in the last few years to account for the IMC [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26], the mechanism behind this effect is not yet fully understood. With this motivation, in this work we study the behavior of strongly interacting matter under an external magnetic field in the framework of nonlocal chiral quark models.…”