The charged inflaton and its gauge fields: preheating and initial
  conditions for reheating
  We calculate particle production during inflation and in the early stages of
reheating after inflation in models with a charged scalar field coupled to
Abelian and non-Abelian gauge fields. A detailed analysis of the power spectra
of primordial electric fields, magnetic fields and charge fluctuations at the
end of inflation and preheating is provided. We carefully account for the Gauss
constraints during inflation and preheating, and clarify the role of the
longitudinal components of the electric field. We calculate the timescale for
the back-reaction of the produced gauge fields on the inflaton condensate,
marking the onset of non-linear evolution of the fields. We provide a
prescription for initial conditions for lattice simulations necessary to
capture the subsequent nonlinear dynamics. On the observational side, we find
that the primordial magnetic fields generated are too small to explain the
origin of magnetic fields on galactic scales and the charge fluctuations are
well within observational bounds for the models considered in this paper.
