Jean-François Paquet

Initial conditions for hydrodynamics from kinetic theory equilibration

Abstract We use effective kinetic theory to study the pre-equilibrium dynamics in heavy-ion collisions. We describe the evolution of linearized energy perturbations on top of out-of-equilibrium background to the energy-momentum tensor at a time when hydrodynamics becomes applicable. We apply this description to IP-Glasma initial conditions and find an overall smooth transition to hydrodynamics. In a phenomenologically favorable range of η / s values, early time dynamics can be accurately described in terms of a few functions of a scaled time variable τ T / ( η / s ) . Our framework can be readily applied to other initial state models to provide the pre-equilibrium dynamics of the energy momentum tensor.

Bulk viscous effects on flow and dilepton radiation in a hybrid approach

Abstract Starting from IP-Glasma initial conditions, we investigate the effects of bulk pressure on low mass dilepton production at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) energies. Though thermal dilepton v 2 is affected by the presence of both bulk and shear viscosity, whether or not these effects can be measured depends on the dilepton “cocktail” contribution to the the low mass dilepton v 2 . Combining the thermal and “cocktail” dileptons, the effects of bulk viscosity on total dilepton v 2 is investigated.

Probing the space-time evolution of heavy ion collisions with photons and dileptons

Abstract Photons and dileptons are emitted throughout the evolution of the deconfined nuclear medium produced in heavy ion collisions. As such they can provide valuable information about the different phases of the medium, and complement hadronic measurements and other observables. In this work, recent developments related to electromagnetic emissions at early times, in the crossover region, and at late times are reviewed. The space-time description of the nuclear medium from a hydrodynamic model of heavy ion collisions is used to provide context and guide the discussion.