PUB - Publikationen an der Universität Bielefeld

We consider moduli fields interacting with thermalized relativistic matter. We determine the temperature dependence of their damping rate and find that it is dominated by thermal effects in the high temperature regime, i.e. for temperatures larger than their mass. For a simple scalar model the damping rate is expressed through the known matter bulk viscosity. The high temperature damping rate is always smaller than the Hubble rate, so thermal effects are not sufficient for solving the cosmological moduli problem.