Exchange driven freeze out of dark matter

TL;DR

This paper proposes a new mechanism where exchange processes within a degenerate dark sector determine the relic density of thermal dark matter, demonstrated through simple scalar models at the GeV scale.

Contribution

It introduces a novel freeze-out mechanism driven by exchange processes in a degenerate dark sector, differing from traditional annihilation-based models.

Findings

Exchange processes can set dark matter relic density in certain models.

Degenerate dark sectors with delayed freeze-out exhibit unique relic density outcomes.

Scalar models at GeV scale validate the proposed mechanism.

Abstract

We introduce a novel mechanism where processes that preserve the number density of the dark sector set the relic density of a thermal particulate dark matter. In a relatively degenerate multipartite dark sector if there is a considerable time lapse between the freeze out of various species then a process like exchange between dark sector constituents can play the pivotal role of driving freeze out and setting dark matter relic density. As a proof of principle, we present simple scalar models with viable dark matter in the GeV scale to demonstrate this phenomenon.