Small-$x$ evolution of jet quenching parameter

Concept of transverse deflection probability of a parton that travels through strongly interacting medium, recently introduced by D'Eramo, Liu and Rajagopal, have been used to derive high energy evolution equation for the jet quenching parameter in stochastic multiple scatterings regime. Jet quenching parameter, ${\hat q}(x)$, appears to evolve with $x$, with an exponent $0.9{\bar \alpha}_s$, which is slightly less than that of $x {\cal G} (x)$ where ${\cal G} (x)$ is the gluon distribution function.