Dark matter in the Higgs resonance region

TL;DR

This paper investigates the singlet scalar Higgs portal dark matter model near the Higgs resonance, combining gamma-ray and cosmic-ray data to explore its viability and future detection prospects.

Contribution

It provides a comprehensive analysis of the Higgs resonance region, incorporating relic density calculations with early kinetic decoupling effects and combining multiple astrophysical data sources.

Findings

Model fits astrophysical data well for all or subdominant relic density fractions.

Resonant annihilation effects are crucial for relic density calculations.

Future experiments could effectively probe these dark matter scenarios.

Abstract

The singlet scalar Higgs portal model provides one of the simplest explanations of dark matter in our Universe. Its Higgs resonant region, $m_\text{DM}\approx m_h/2$, has gained particular attention, being able to reconcile the tension between the relic density measurement and direct detection constraints. Interestingly, this region is also preferred as an explanation of the Fermi-LAT $\gamma$-ray Galactic center excess. We perform a detailed study of this model using $\gamma$-ray data from the Galactic center and from dwarf spheroidal galaxies and combine them with cosmic-ray antiproton data from the AMS-02 experiment that shows a compatible excess. In the calculation of the relic density, we take into account effects of early kinetic decoupling relevant for resonant annihilation. The model provides excellent fits to the astrophysical data either in the case the dark matter candidate constitutes all or a subdominant fraction of the observed relic density. We show projections for future direct detection and collider experiments to probe these scenarios.