Gravity-Higgs portal for dark matter decay

TL;DR

This paper explores how nonminimal coupling between the Higgs field and gravity creates additional decay pathways for gravitational dark matter, affecting decay signatures and dominant channels across different mass ranges.

Contribution

It introduces the concept of gravity-Higgs portals and analyzes their impact on dark matter decay, highlighting differences between scalar and fermionic candidates.

Findings

Decay branching ratios are nearly independent of decay pathways for scalar dark matter below 5 TeV.

Fermionic dark matter decay products differ between MD and AD, with AD producing only neutrinos and Higgs bosons.

Gravity-Higgs portals tend to dominate decay at around several hundred GeV.

Abstract

Dark matter can decay via gravity portals and contribute a minor decay (MD) width. This paper proposes that nonminimal coupling between the Higgs field and gravity can lead to additional gravity-Higgs portals for gravitational dark matter to decay and contribute additional decay (AD) width. For scalar dark matter candidates with a mass less than 5 TeV, the decay branching ratios are almost independent of whether dark matter decay through gravity portals or gravity-Higgs portals; therefore, it is almost impossible to distinguish gravity portals from gravity-Higgs portals by observing decay products. For fermionic singlet dark matter candidates, their MD products are diverse, while their AD products are monotonous, only neutrinos and Higgs bosons. As for both dark matter candidates, gravity-Higgs portals prefer to dominate the decay at around several hundred GeV. Besides, for both TeV dark matter candidates, there is still a vast parameter space alive.