Dark Matter Abundance from Sequential Freeze-in Mechanism

Understand

We present a thorough analysis of the sequential freeze-in mechanism for dark matter production in the early universe.

• In this mechanism the dark matter relic density results from pair annihilation of mediator particles which are themselves produced by thermal collisions of standard model particles.
• Below some critical value of the mediator coupling to standard model fields, this sequential channel dominates over the usual freeze-in where dark matter is directly produced from thermal collisions, even when the mediator is not in thermal equilibrium.
• The latter case requires computing the full non-thermal distribution of the mediators, for which finite temperature corrections are particularly important.