Freezing-in Cannibal Dark Sectors

TL;DR

This paper explores how feeble Higgs portal interactions enable dark matter production via freeze-in, with various scalar models showing viable cannibal phases and distinct detection signatures, impacting cosmological bounds and experimental prospects.

Contribution

It provides a comprehensive analysis of three scalar dark matter models with freeze-in production and cannibal phases, including their detection prospects and cosmological implications.

Findings

Viable dark matter candidates exist in all models.

Cosmological bounds vary with dark sector interactions.

Potential signatures in long-lived particle and indirect detection experiments.

Abstract

Self-Interacting Dark Matter models can successfully explain dark matter (DM) production through interactions confined within the dark sector. However, they often lack measurable experimental signals due to their secluded nature. Including a feeble interaction with the visible sector through a Higgs portal leads not only to potential detection avenues and richer thermal production dynamics, but also to a possible explanation of the initial dark sector population through the freeze-in mechanism. In this work we study, by solving the full system of coupled Boltzmann equations for the number densities and temperatures of all the involved states, three scenarios of this type where the DM is: a real scalar with broken $\mathbb{Z}_2$, a complex scalar with unbroken $\mathbb{Z}_3$, and a $\mathbb{Z}_3$ scalar with an additional scalar mediator. All of these models have viable dark matter candidates in a cannibal phase while having different detection profiles. We show that cosmological bounds can be either exacerbated or evaded by changing the dark sector interactions, leading to potential signatures in long-lived particle and indirect detection experiments.