Dark matter production and reheating via direct inflaton couplings: collective effects

Understand

We study scalar dark matter production and reheating via renormalizable inflaton couplings, which include both quartic and trilinear interactions.

• These processes often depend crucially on collective effects such as resonances, backreaction and rescattering of the produced particles.
• To take them into account, we perform lattice simulations and map out parameter space producing the correct (non-thermal) dark matter density.
• We find that the inflaton-dark matter system can reach a quasi-equilibrium state during preheating already at very small couplings, in which case the dark matter abundance becomes independent of the inflaton-dark matter coupling and is described by a universal formula.