Thermal particle production in cosmology and quark-gluon plasma
Prof. Dr. Mikko Laine (Universität Bern)

If a multiparticle system contains different particle species, some interacting strongly and others weakly, then a typical situation is that the strongly interacting particles form a thermalized medium with which we can associate a temperature T, whereas the weakly interacting particles are said to be "out of equilibrium". Nevertheless the weakly interacting particles play an important physical role, for instance they could represent Dark Matter in cosmology, or a "Hard Probe" in a heavy ion collision experiment. In this talk some physically relevant situations of this type are described, and recent results as well as theoretical challenges faced by computations concerning the production rate of the weakly interacting particles are outlined.