Jet quenching parameter in an expanding QCD plasma

Understand

We study the phenomenon of transverse momentum broadening for a high-$p_T$ parton propagating through a weakly-coupled quark-gluon plasma undergoing boost-invariant longitudinal expansion.

• We propose a boost-invariant description for this phenomenon, in which the broadening refers to the angular variables $\eta$ (the pseudo-rapidity) and $\phi$ (the azimuthal angle).
• The jet quenching parameter $\hat{q}$ which enters this description depends upon the proper time alone.
• We furthermore consider radiative corrections to $\hat q$.