Light Dark Matter from Inflaton Decay

Understand

We propose a simple mechanism of light dark matter (DM) production from the decay of the oscillating inflaton condensation.

• If the reheating temperature after inflation is higher than the inflaton mass, which is of the same order of the momentum of the DM at the time of the production, the DM momentum can be suppressed compared to the temperature of the thermal plasma if the interaction of the DM is weak enough.
• Consequently, the DM can be cold enough to avoid the observational constraints on the warm DM, like the Lyman-$\alpha$ bound even if the DM mass is small.
• We study the bosonic and fermionic DM production from the inflaton decay, taking into account the effect of the stimulated emission and Pauli blocking, respectively.