Non-equilibrium evolution of quantum fields during inflation and late accelerating expansion.
We consider a toy model including 3 scalar fields with different masses to study formation of a light axion-like condensate presumed to be responsible for inflation and/or late accelerating expansion of the Universe. The investigation is performed in the framework of non-equilibrium quantum field theory in a consistently evolved FLRW geometry. We discuss in details how the initial conditions for such a model must be defined in a fully quantum setup and show that in a multi-component model coupling between fields highly reduce the number of independent initial degrees of freedom. Numerical simulation of this model shows that it can be fully consistent with present cosmological observations. Moreover, we find that quantum effects rather than effective potential of a condensate is the dominate contributor in energy density and in triggering inflation and late accelerating expansion. The light scalar field, both in condensate and perturbatively free particles has a crucial role in controlling the trend of heavier fields. Up to precision of our simulations we do not find any IR singularity during inflation. These findings highlight uncertainties of attempts to extract information about physics of early Universe by naively comparing predictions of local effective classical models with cosmological observations, neglecting inherently non-local nature of quantum processes.
Publisher URL: http://arxiv.org/abs/1711.01925
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