Nonequilibrium quantum dynamics of phase transitions in an expanding universe

Abstract

I summarize the derivation of a set of Feynman rules appropriate for the perturbative description of the nonequilibrium dynamics of the symmetry-breaking phase transition in $\lambda {\varphi }^4$ theory in a Robertson-Walker universe. The approximation scheme I develop provides for a treatment of dissipative effects which are essential to an adequate description of the nonequilibrium state. It also provides for the emergence from an initially symmetric state of a final state exhibiting the properties of spontaneous symmetry breaking without the introduction by hand of any explicit symmetry breaking.

Comments: 7pages, using RevTeX, no figures. Contribution to 5th International Workshop on Thermal Field Theories (Regensburg, August 1998). A few explanatory remarks added