The chromo-Weibel instability in an expanding background

TL;DR

This paper reviews recent numerical studies of the chromo-Weibel instability in an expanding quark-gluon plasma, showing rapid longitudinal thermalization despite persistent momentum anisotropy.

Contribution

It presents a detailed numerical analysis of the chromo-Weibel instability in an expanding background, highlighting the role of non-linear mode couplings in plasma thermalization.

Findings

Rapid longitudinal thermalization occurs despite sustained momentum anisotropy.

Unstable plasma modes regenerate longitudinal pressure.

System maintains high momentum-space anisotropy during evolution.

Abstract

In this proceedings contribution we review recent calculations of the dynamics of the chromo-Weibel instability in the quark gluon plasma. This instability is present in gauge theories with a one-particle distribution function which is momentum-space anisotropic in the local rest frame. The conditions necessary for triggering this instability can be present already in the color-glass-condensate initial state or dynamically generated by the rapid longitudinal expansion of the matter created in a heavy-ion collision. Using the hard-loop framework we study the case that the one-particle distribution function possesses an arbitrary initial momentum anisotropy that increases in time due to longitudinal free streaming. The resulting three-dimensional dynamical equations for the chromofield evolution are solved numerically. We find that there is regeneration of the longitudinal pressure due to unstable plasma modes; nevertheless, the system seems to maintain a high-degree of momentum-space anisotropy. Despite this anisotropy, we find that there is rapid longitudinal thermalization of the plasma due to the non-linear mode couplings inherent in the unstable evolution.