Magnetic susceptibility of a strongly interacting thermal medium with 2 + 1 quark flavors

Abstract

Thermodynamics of the three-flavor quark-meson model with U A (1) anomaly is studied in the presence of external magnetic fields. The nonperturbative functional renormalization group is employed in order to incorporate quantum and thermal fluctuations beyond the mean-field approximation. We calculate the magnetic susceptibility with proper renormalization and find that the system is diamagnetic in the hadron phase and paramagnetic in the hot plasma phase. The obtained values of the magnetic susceptibility are in reasonable agreement with the data from first-principle lattice QCD. Comparison with the mean-field approximation, the Hadron Resonance Gas model and a free gas with temperature-dependent masses is also made.

New insight about the effective restoration of UA(1) symmetry

“…It's well known that mesons such as pion dominate at low temperature and their fluctuations will affect the system significantly (see, e.g., Refs. [49,50]). Thus the FRG approach is usually known to be a method beyond mean-field approximation.…”

Thermodynamics of 2+1 flavor Polyakov-loop quark-meson model under external magnetic field

“…(10) and implementing the optimized regulators taken in Refs. [10,59,68,95], one can obtain an analytic flow equation for the U k as…”

“…The specific form of the Hessian matrix is quite complicated and can be found in Refs. [68,88]. The Polyakov-loop potential V poly also needs to be specified for solving Eq.…”

Magnetic Catalysis in the Higher-Order Quark Sigma Model

“…The study of the influence of external magnetic fields on the fundamental properties of quantum chromodynamic (QCD) theory, confinement and dynamical chiral symmetry breaking is still a matter of great interest both in theoretical and experimental activities [18,19,20,21]. The chiral symmetry structure in the original sigma model within the presence of an external uniform magnetic field is investigated [22].…”