Speaker
Description
We investigate viscous effects on heavy-quark (HQ) transport and thermal dilepton production in an evolving quark gluon plasma (QGP) using the Chapman-Enskog (CE) framework up to second order in gradients. Employing temperature and shear-stress profiles from causal dissipative relativistic hydrodynamics, we compare the CE results with those from Grad’s 14-moment approximation. For HQ transport, the CE corrections substantially suppress the drag force and induce a non-trivial momentum dependence in transverse momentum diffusion, while producing a comparatively smaller modification of longitudinal diffusion. For thermal dileptons, the CE corrections enhance the early-time contribution, with the effect decreasing as the QGP evolves and approaching the first-order CE result. We find that the impact of viscous corrections on observables is determined not only by their magnitude but also by their momentum dependence and the momentum weighting of the underlying transport and emission processes. These results demonstrate that the momentum structure of viscous corrections at the distribution-function level is not directly reflected in different observables, which probe distinct regions of momentum space.