  We consider one-loop thermal effects on the decay of a scalar field zero mode
initially dominating the energy density of the universe. We assume fermionic
decay channels and take into account the effects due to both particle and hole
excitations, and present approximate expressions for the absorption and decay
rates. We apply the results to the inflaton and solve the Boltzmann equations
to find the temperature evolution of the fermionic plasma. We show that the
reheat temperature can be greater than the inflaton mass if the inflaton decays
into more than one fermionic species.
