On finite density effects on cosmic reheating and moduli decay and implications for Dark Matter production

Understand

We study the damping of an oscillating scalar field in a Friedmann-Robertson-Walker spacetime by perturbative processes, taking into account the finite density effects that interactions with the plasma of decay products have on the damping rate.

• The scalar field may be identified with the inflaton, in which case this process leads to the reheating of the universe after inflation.
• It can also resemble a modulus that dominates the energy density of the universe at later times.
• We find that the finite density corrections to the damping rate can have a drastic effect on the thermal history and considerably increase both, the maximal temperature in the early universe and the reheating temperature at the onset of the radiation dominated era.