Relaxation processes in a condensed Bose gas

We develop, on the basis of the self-consistent mean-field approximation, the kinetic theory for a dilute Bose gas below the Bose-Einstein transition temperature. The collision operator in the Boltzmann equation is calculated by golden rule arguments, and the momentum and temperature dependences of the scattering rates are determined. As an application, we consider the relaxation of a nonequilibrium distribution of the quasiparticles. We discuss the relevance of our calculation for the (hypothetical) condensed state of spinpolarized hydrogen.Zur Erlangung der Lehrbefähigung für das Lehrgebiet Physik der Fakultät für Physik der Universität Karlsruhe vorgelegte Habilitationsschrift.