Inflation-Dark Matter unified through Quantum Generation
  We unify inflation and dark matter via a single scalar field phi. One of the
main difficulties for this unification is that between inflation and dark
matter one needs a successful reheating process and a long lasting period of
radiation. Therefore the amount of energy density in the inflaton-dark matter
field phi must be fine tune after reheating to give dark matter. Here we show
an alternative scheme in which the inflaton decays completely, disappearing
entirely from the spectrum. However, at low energies, before matter-radiation
equality, the same interaction term that leads to the inflaton decay,
regenerates phi. An essential feature is that the transition between the
intermediate radiation dominated to the dark matter phase is related to a
quantum generation of the scalar field \phi instead to purely classical
dynamics. Thanks to this quantum transition the inflation-dark matter
unification can take place naturally without fine tuning. The unification
scheme presented here has three parameters, the mass of the dark matter
particle m_o, the inflation parameter lambda and the coupling g for the
inflaton interaction. Phenomenology fixes the value for lambda and gives a
constraint between g and m_o, leaving only the mass of the dark matter particle
m_o as a free parameter. These same three parameters lambda, m_o, g are present
in models with inflation and a dark matter wimp particle but without
unification. Therefore our unification scheme does not increase the number of
parameters and it accomplishes the desired unification between inflaton and
dark matter for free.
