Resonant Assisted Annihilation

Understand

Assisted annihilation is a novel mechanism to generate viable sub-GeV thermal dark matter, where a pair of stable dark matter annihilates with an assister to Standard Model states.

• Typically such $3 \to 2$ annihilation topologies are flux suppressed compared to $2 \to 2$ processes.
• In this paper, we explore the possibility of a resonant $3 \to 2$ assisted annihilation dominantly driving the freeze-out of dark matter.
• We demonstrate that in a simple multipartite scalar extension of the Standard Model this can be realized in certain regions of parameter space to provide viable dark matter relic density, in agreement with observation.