Initial conditions for heavy ion collisions with QCD kinetic theory

We employ the leading order QCD kinetic theory to describe a consistent matching betweenthe initial stage of a heavy ion collision and the subsequent hydrodynamic evolution. We usethe linearized kinetic response functions around the non-equilibirum longitudinally expandingbackground to map initial energy and momentum perturbations to the energy momentum tensorat hydrodynamic initialization time τ hydro . We check that hadronic observables then becomerather insensitive to the cross-over time between kinetic theory and viscous hydrodynamics. Theuniversal scaling of kinetic response in units of kinetic relaxation time allows for astraightforward application of kinetic pre-equilibration event-by-event.