We study hard real photon production, dilepton emission, and the collisional energy loss as valuable observables in heavy ion physics. In order to make theoretical predictions more valuable in addressing experimental situations, we attempt to derive respective rates for a situation where the system is away from (chemical) equilibrium.

From the theoretical point of view we assume chemical non-equilibrium as an interesting simplified scenario in which to study consequences of violation of detailed balance characteristic of a system away from equilibrium.

I report on work done within the Closed-Time-Path formalism to lowest order in an expansion for the gradients of chemical equilibration and within a perturbative expansion eventually including resummation of leading Hard-Thermal-Loop (HTL) contributions.

Our results include predictions for the rate of hard real photon production from the QGP, as well as the rate of collisional energy loss for a heavy quark traversing a QCD medium respectively as a function of fugacity parameters describing the deviation from equilibrium. It is shown that all singularities appearing in fixed leading order calculations are dynamically screened also in the off-equilibrium case upon resummation of HTL. With regard to the production of dileptons we note that on-shell exchange involved in the underlying process could lead to interesting non-equilibrium effects that deserve further investigation.

Individual aspects reported on here have been written down, e.g., in: hard real photons , energy-loss , dileptons