Neil Barnaby, Ryo Namba, Marco Peloso
In any realistic particle physics model of inflation, the inflaton can be
expected to couple to other fields. We consider a model with a dilaton-like
coupling between a U(1) gauge field and a scalar inflaton. We show that this
coupling can result in observable non-gaussianity of characteristic and nearly
local shape, even in the conventional regime where inflation is supported by a
single scalar slowly rolling on a smooth potential: the time dependent inflaton
condensate leads to amplification of the large-scale gauge field fluctuations,
which can feed-back into the scalar/tensor cosmological perturbations.
Observable non-gaussianity is obtained in a regime where perturbation theory is
under control. If the gauge field is identified with the electromagnetic field,
the model that we study is a realization of the magnetogenesis idea originally
proposed by Ratra, and widely studied. This identification (which is not
necessary for the non-gaussianity production) is however problematic in light
of a strong coupling problem already noted in the literature.
View original:
http://arxiv.org/abs/1202.1469
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