Minimal self-interacting dark matter models with light mediator

TL;DR

This paper explores minimal self-interacting dark matter models with light mediators, proposing scenarios where dark matter and mediators have lower temperatures or different annihilation channels to satisfy constraints.

Contribution

It identifies new minimal models of self-interacting dark matter with light mediators that evade existing constraints through temperature differences or alternative annihilation pathways.

Findings

Models with lower dark sector temperatures are viable.

Dark matter can annihilate into heavier particles instead of mediators.

Multiple mediator types, scalar and vector, are considered with various coupling hierarchies.

Abstract

The light mediator scenario of self-interacting dark matter is strongly constrained in many ways. After summarizing the various constraints, we discuss minimal options and models which allow to nevertheless satisfy all these constraints. One straightforward possibility arises if the dark matter and light mediator particles have a temperature sizably smaller than the SM particles. Another simple possibility arises if dark matter doesn't annihilate dominantly into a pair of light mediators but into heavier particles. Both possibilities are discussed with scalar as well as vector boson light mediators. Further possibilities, such as with a hierarchy of quartic scalar couplings, are also identified.