Development of equilibrium after preheating - art. no. 103503

We present a fully nonlinear study of the development of equilibrium after preheating. Preheating is the exponentially rapid transfer of energy from t he nearly homogeneous inflaton field to fluctuations of other fields and/or the inflaton itself. This rapid transfer leaves these fields in a highly n onthermal state with energy concentrated in infrared modes. We have perform ed lattice simulations of the evolution of interacting scalar fields during and after preheating for a variety of inflationary models. We have formula ted a set of generic rules that govern the thermalization process in all of these models. Notably, we see that once one of the fields is amplified thr ough parametric resonance or other mechanisms, it rapidly excites other cou pled fields to exponentially large occupation numbers. These fields quickly acquire nearly thermal spectra in the infrared, which gradually propagates into higher momenta. Prior to the formation of total equilibrium, the exci ted fields group into subsets with almost identical characteristics (e.g. g roup effective temperature). The way fields form into these groups and the properties of the groups depend on the couplings between them. We also stud ied the onset of chaos after preheating by calculating the Lyapunov exponen t of the scalar fields.