Impact of magnetic field on shear viscosity of quark matter in Nambu-Jona-Lasinio model

TL;DR

This paper studies how strong magnetic fields influence the shear viscosity of quark matter using the Nambu-Jona-Lasinio model, revealing anisotropic effects and different regimes depending on the magnetic field strength and quark widths.

Contribution

It provides a detailed analysis of shear viscosity components in magnetized quark matter within the NJL model, including strong and large thermal width limits, highlighting anisotropic effects.

Findings

Shear viscosity splits into multiple components under magnetic fields.

In strong fields, viscosity components merge into fewer due to anisotropy.

Thermal width influences the applicability of simplified viscosity expressions.

Abstract

We have investigated shear viscosity of quark matter in presence of a strong uniform magnetic field background where Nambu-Jona-Lasinio model has been considered to describe the magneto-thermodynamical properties of the medium. In presence of magnetic field, shear viscosity coefficient gets split into different components because of anisotropy in tangential stress of the fluid. Four different components can be merged to two components in limit of strong field, where collisional width of quark becomes much lower than its synchrotron frequency. A simplified contact diagram of quark-quark interaction can estimate a small collisional width, where strong field limit expressions are exactly applicable. Although, for RHIC or LHC matter, one can expect a large thermal width, for which generalized four components viscosities are necessary. We have explored these all different possible cases in the thermodynamical framework of Nambu-Jona-Lasinio model.