http://arxiv.org/abs/1905.12562
We study the post-inflation dynamics of multifield models involving nonminimal couplings using lattice simulations to capture significant nonlinear effects like backreaction and rescattering. By investigating the late-stage nonlinear dynamics, we measure the effective equation of state and typical time-scales for the onset of thermalization, quantities that could affect the usual mapping between predictions for primordial perturbation spectra and measurements of anisotropies in the cosmic microwave background radiation. For large values of the nonminimal coupling constants, we find efficient particle production that gives rise to nearly instantaneous preheating. Moreover, the strong single-field attractor behavior that was identified for these models in linearized analyses remains robust in the full theory, and in all cases considered the attractor persists until the end of preheating. The persistence of the single-field attractor is significant because it suppresses typical signatures of multifield models. We therefore find that even taking into account the violent preheating phase after inflation, predictions for primordial observables in this class of models retain a close match to the latest observations.
R. Nguyen, J. Vis, E. Sfakianakis, et. al.
Thu, 30 May 19
36/57
Comments: 6 pages, 7 figures
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