Kinetic evolution of the glasma and thermalization in heavy ion collisions

摘要

In relativistic heavy ion collisions, a highly occupied gluonic matter iscreated shortly after initial impact, which is in a non-thermal state and oftenreferred to as the Glasma. Successful phenomenology suggests that the glasmaevolves rather quickly toward the thermal quark-gluon plasma and a hydrodynamicbehavior emerges at very early time $\sim \hat{o}(1)$ fm/c. Exactly how such"apparent thermalization" occurs and connects the initial conditions to thehydrodynamic onset, remains a significant challenge for theory as well asphenomenology. We briefly review various ideas and recent progress inunderstanding the approach of the glasma to the thermalized quark-gluon plasma,with an emphasis on the kinetic theory description for the evolution of suchfar-from-equilibrium and highly overpopulated, thus weakly-coupled yet stronglyinteracting glasma.