Conformal Portal to Dark Matter

TL;DR

This paper introduces a new conformal portal coupling to dark matter via the Ricci scalar, enabling freeze-in production and offering testable predictions for direct detection experiments.

Contribution

It proposes a novel conformal portal mechanism connecting dark matter to the Standard Model through the Ricci scalar, with two concrete realizations.

Findings

Feeble portal coupling allows freeze-in dark matter production.

Conformally induced Higgs portal compatible with Higgs inflation.

Mediator portal can be tested by direct detection experiments.

Abstract

We propose a new portal coupling to dark matter by taking advantage of the nonminimally coupled portal sector to the Ricci scalar. Such a portal sector conformally induces couplings to the trace of the energy-momentum tensor of matters including highly secluded dark matter particles. The portal coupling is so feeble that dark matter is produced by freeze-in processes of scatterings and/or the decay of the mediator. We consider two concrete realizations of the portal: conformally induced Higgs portal and conformally induced mediator portal. The former case is compatible with the Higgs inflation, while the latter case can be tested by dark matter direct detection experiments.