Viscous Leptons in the Quark Gluon Plasma

TL;DR

This paper analyzes the shear viscosity of leptons in a strongly coupled quark-gluon plasma, revealing how lepton viscosity relates to electrical conductivity and impacts energy loss, with implications for understanding plasma behavior.

Contribution

It introduces a novel relation between lepton shear viscosity and the plasma's electrical conductivity, utilizing gauge/gravity duality to explore strongly coupled plasma effects.

Findings

Lepton shear viscosity is inversely proportional to electrical conductivity over temperature.

Leptons form a more viscous fluid than quarks by a large ratio.

Energy loss of hard leptons is enhanced in strongly coupled plasma.

Abstract

We investigate the shear viscosity of leptons in a strongly coupled quark gluon plasma (QGP). We find that the shear viscosity due to the lepton-quark scattering is inversely proportional to the ratio of electric conductivity of the QGP to temperature up to the leading logarithmic order of the electromagnetic coupling. The finding implies that the thermal leptons form a more viscous fluid than the quarks by a large ratio. Using the known result for the electrical conductivity of strongly coupled plasmas obtained from gauge/gravity duality, we find that the lepton shear viscosity is suppressed compared with the one from lepton-lepton scattering. Consistently, we find an enhancement of the energy loss of hard leptons in a strongly coupled scenario compared with that in a weakly coupled plasma.