Challenges for Inflaton Dark Matter
  We examine an intriguing possibility that a single field is responsible for
both inflation and dark matter, focussing on the minimal set-up where inflation
is driven by a scalar coupling to curvature. We study in detail the reheating
process in this framework, which amounts mainly to particle production in a
quartic potential, and distinguish thermal and non-thermal dark matter options.
In the non-thermal case, the reheating is impeded by backreaction and
rescattering, making this possibility unrealistic. On the other hand,
thermalized dark matter is viable, yet the unitarity bound forces the inflaton
mass into a narrow window close to half the Higgs mass.
