Scalar singlet dark matter in non-standard cosmologies

TL;DR

This paper investigates how non-standard cosmological expansion histories affect the production and abundance of scalar singlet dark matter via freeze-out and freeze-in mechanisms, impacting detection prospects.

Contribution

It introduces the effects of non-standard expansion on scalar singlet dark matter production, showing significant changes in required couplings and observational implications.

Findings

Non-standard expansion can increase freeze-in portal couplings.

Non-standard expansion allows smaller freeze-out couplings.

Altered cosmology impacts direct detection prospects.

Abstract

We study production of dark matter (DM) in models with a non-standard expansion history. We consider both freeze-out and freeze-in mechanisms for producing the observed DM abundance in a model where the DM consists of scalar singlet particles coupled to the Standard Model sector via the Higgs portal. We show that a non-standard expansion phase can lead to a significant change in the DM abundance and therefore to observational ramifications. For example, for DM freeze-in the required portal coupling can be much larger, whereas for DM freeze-out much smaller values become allowed. We evaluate the relevant constraints and discuss prospects for direct detection of such DM.