Spinodal decomposition and inflation: Dynamics and metric perturbations - art. no. 023520

We analyze the dynamics of spinodal decomposition in inflationary cosmology using the closed time path formalism of out of equilibrium quantum field t heory combined with the non-perturbative Hartree approximation. Ln addition to a general analysis. we compute the detailed evolution of two inflationa ry models of particular importance: lambda Phi(4) new inflation and natural inflation. We compute the metric fluctuations resulting from inflationary phase transitions in the slow roll approximation, showing that there exists a regime for which quantum fluctuations of the inflaton field result in a significant deviation in the predictions of the spectrum of primordial dens ity perturbations from standard results. We provide case examples for which a blue tilt to the power spectrum (i.e. n(s) >1) results from the evolutio n of a single inflaton held, and demonstrate that field fluctuations may re sult in a scalar amplitude of fluctuations significantly below standard pre dictions, resulting in a slight alleviation of the inflationary fine-tuning problem. We show explicitly that the metric perturbation spectrum resultin g from inflation depends upon the state at the outset of the inflationary p hase.