Kination and the Inert Doublet Model

TL;DR

This paper explores how a stiff equation of state like kination can make the inert doublet model's dark matter candidate viable in the 120-500 GeV mass range, satisfying experimental constraints.

Contribution

It demonstrates that kination cosmology allows the inert doublet dark matter to be underabundant in standard cosmology to become viable, expanding the model's parameter space.

Findings

Dark matter freeze-out during kination makes the 120-500 GeV mass window viable.

The scenario satisfies current experimental constraints.

Upcoming detection efforts can test this model.

Abstract

The inert doublet model is a two-Higgs-doublet extension of the standard model that provides a minimal and versatile framework for frozen-out dark matter. Assuming standard cosmology, if the dark matter mass ranges between approximately 120 GeV and 500 GeV then it turns out to be underabundant, as gauge interactions render its annihilation too efficient. In this work, we show that this mass window becomes allowed in cosmological scenarios where dark matter freeze-out occurs during a period with a stiff equation of state, $w > 1/3$, such as kination. This predictive setup satisfies all current experimental constraints while remaining within the reach of upcoming detection efforts.