Affine gravitational scenario for dark matter decay

TL;DR

This paper proposes a novel affine gravity-based model where dark matter couples to spacetime affine connection, leading to decay into standard model particles via the Higgs portal, with implications for collider production and observational constraints.

Contribution

It introduces a new dark matter coupling mechanism through affine gravity, linking dark matter decay and production to the Higgs portal, differing from standard metric-based models.

Findings

Dark matter decays into standard model particles via Higgs portal.

Bounds on nonminimal coupling consistent with observational data.

Potential for collider production of sub-10 GeV dark matter.

Abstract

Since the current evidence of its existence is revealed only through its gravitational influence, the way dark matter couples to gravity must be then of primary importance. Here, unlike the standard model sector which is typically coupled to metric, dark matter is supposed to couple only to spacetime affine connection through a $Z_2$-symmetry breaking term. We show that this structure leads to a coupling between dark matter, which is considered scalar, and the standard model Higgs potential. This induces dark matter decays into standard model particles through the Higgs which acts as a portal between the visible and the dark sectors. We study thoroughly the resulting decay modes for various mass ranges, and provide relevant bounds on the nonminimal coupling to affine gravity in line with observational data. Moreover, we find that the coupling to Higgs can be sufficiently large to facilitate production of dark matter lighter than 10 GeV at current and future high energy colliders.