Shear viscosity coefficient of magnetized QCD medium near chiral phase transition

TL;DR

This paper investigates how strong magnetic fields influence the shear viscosity of quark matter near the chiral phase transition, revealing anisotropic effects and phase transition signatures using a modified NJL model.

Contribution

It introduces a detailed analysis of shear viscosity components in magnetized quark matter near phase transitions, incorporating inverse magnetic catalysis effects fitted to LQCD data.

Findings

Shear viscosity components decrease with magnetic field strength.

Discontinuities in viscosity components occur at first order phase transition.

Viscosity increases with temperature and shows anisotropic behavior in strong magnetic fields.

Abstract

We study the properties of the shear viscosity coefficient of quark matter at finite temperature and chemical potential near chiral phase transition in a strong background magnetic field. A strong magnetic field induces anisotropic features, phase-space Landau-level quantization, and if the magnetic field is sufficiently strong, interferes with prominent QCD phenomena such as dynamical quark mass generation, likely affecting the quark matter transport characteristics. The modified Nambu-Jona-Lasinio (NJL) model with inverse magnetic catalysis effect by fitting the Lattice QCD (LQCD) results is used to calculate the changes of quasiparticle related thermodynamic quantities, and the shear viscosity of the system medium, which is analyzed under the relaxation time approximation. We quantify the influence of the order of chiral phase transition and the critical endpoint on dissipative phenomena in such a magnetized medium. When the magnetic field exists, the shear viscosity coefficient of the dissipative fluid system can be decomposed into five different components. In strong field limit, we make a detailed study of the dependencies of $\eta_{2}$ and $\eta_{4}$ on temperature and magnetic field for the first order phase transition and critical endpoint transition. respectively. It is found that $\eta_{2}$ and $\eta_{4}$ both decrease with magnetic field and increase with temperature, and the discontinuities of $\eta_{2}$ and $\eta_{4}$ occur at the first order phase transition point.