Secretly Asymmetric Dark Matter

TL;DR

This paper introduces a mechanism where dark matter asymmetries originate in the early universe, allowing for symmetric dark matter today with high annihilation rates, demonstrated through a flavored dark matter model.

Contribution

It presents a novel mechanism for dark matter asymmetry generation that does not require a net dark matter number throughout cosmic history.

Findings

Dark matter can be symmetric today despite early asymmetries.

Annihilation rates can exceed those of thermal WIMPs.

Experimental signatures mainly involve the annihilation of the symmetric component.

Abstract

We study a mechanism where the dark matter number density today arises from asymmetries generated in the dark sector in the early universe, even though total dark matter number remains zero throughout the history of the universe. The dark matter population today can be completely symmetric, with annihilation rates above those expected from thermal WIMPs. We give a simple example of this mechanism using a benchmark model of flavored dark matter. We discuss the experimental signatures of this setup, which arise mainly from the sector that annihilates the symmetric component of dark matter.