Jet momentum broadening during initial stages in heavy-ion collisions

Abstract

In ultra-relativistic heavy-ion collisions, the measurement of particle showers known as jets provides crucial insights into the evolution of the quark-gluon plasma. Jets originate from a hard parton created in the initial hard collision and, due to their early creation, can probe also the pre-equilibrium stages of the plasma. Medium modifications to the jet evolution are commonly encoded in the jet quenching parameter $\hat q$. In this talk, I want to discuss our approach to extracting this parameter $\hat q$ during the initial pre-equilibrium stages of heavy-ion collisions. For this, we use the QCD effective kinetic theory description of the anisotropic quark-gluon plasma. We find that we can smoothly close the gap in the literature between the early glasma stage of the collision and the onset of hydrodynamics and that $\hat q$ during the bottom-up kinetic scenario shows little sensitivity to the initial conditions, jet energies, and models of the transverse momentum cutoff. Similarly to the glasma case, we also observe that the jet quenching parameter is enhanced along the beam axis compared to the transverse direction during most of the kinetic evolution. Our results, presented in this talk, are primarily based on our recent work available on arXiv:2303.12595