Hall Viscosity in the Quark-Gluon Plasma

TL;DR

This paper investigates the Hall viscosity in the quark-gluon plasma created in heavy-ion collisions, highlighting its potential impact on flow observables and its comparable magnitude to shear viscosity.

Contribution

It extends kinetic theory to three dimensions to estimate Hall viscosities and explores their effects in realistic QGP conditions.

Findings

Hall viscosities are comparable to shear viscosity at zero magnetic field.

Hall viscous stresses can significantly influence hydrodynamic initial conditions.

Observable effects on flow and event-plane correlations are identified.

Abstract

We study the Hall viscosity of the quark gluon plasma (QGP) created in non-central heavy-ion collisions. In the presence of a strong magnetic field or vorticity, rotational symmetry is broken from O(3) to O(2), allowing for two independent Hall viscosities associated with shear deformations transverse and parallel to the symmetry-breaking direction. We find the corresponding constitutive relations by extending the kinetic-theory mechanism to three spatial dimensions and provide parametric estimates of the Hall viscosities under realistic QGP conditions. Both kinetic-theory and holographic estimates indicate that Hall viscosities are comparable in magnitude to the shear viscosity at zero magnetic field. We further show that Hall viscous stresses at hydrodynamic initialization can be as large as standard viscous corrections and identify observable consequences in flow and event-plane correlations.