Negative Off-Diagonal Conductivities in a Weakly Coupled Quark Gluon Plasma

TL;DR

This paper calculates the conductivity matrix of a weakly coupled quark-gluon plasma, revealing negative off-diagonal conductivities that imply potential gradients can induce counterintuitive currents among different flavors.

Contribution

It provides the first calculation of off-diagonal conductivities in a quark-gluon plasma at leading-log order, highlighting a novel negative off-diagonal behavior.

Findings

Off-diagonal conductivities are negative or zero when chemical potentials are equal.

Potential gradients of one flavor can induce backward currents in others.

The phenomenon may be observable in cold atom experiments.

Abstract

We calculate the conductivity matrix of a weakly coupled quark-gluon plasma at the leading-log order. By setting all quark chemical potentials to be identical, the diagonal conductivities become degenerate and positive, while the off-diagonal ones become degenerate but negative (or zero when the chemical potential vanishes). This means a potential gradient of a certain fermion flavor can drive backward currents of other flavors. A simple explanation is provided for this seemingly counter intuitive phenomenon. It is speculated that this phenomenon is generic and most easily measured in cold atom experiments.