Disformal Dark Matter

TL;DR

This paper explores a two-metric framework for dark matter production, involving conformal and disformal couplings, and investigates how scalar mediators can produce dark matter in the early universe, including effects of reheating.

Contribution

It introduces a generalized two-metric approach to dark matter production, connecting UV theories with FIMP scenarios involving scalar mediators and high suppression scales.

Findings

Dark matter can be produced via scatterings and inflaton decay in this framework.

The scalar mediator can have a suppression scale near the Planck scale.

Reheating effects significantly influence dark matter abundance.

Abstract

We generalize dark matter production to a two-metric framework whereby the physical metric, which couples to the Standard Model (SM), is conformally and/or disformally related to the metric governing the gravitational dynamics. We show that this setup is naturally present in many Ultra Violet (UV) constructions, from K\"ahler moduli fields to tensor-portal models, and from emergent gravity to supergravity models. In this setting we study dark matter production in the early Universe resulting from both scatterings off the thermal bath and the radiative decay of the inflaton. We also take into account non-instantaneous reheating effects at the end of inflation. In this context, dark matter emerges from the production of the scalar field mediating the conformal/disformal interactions with the SM, i.e. realising a Feebly Interacting Matter Particle (FIMP) scenario where the suppression scale of the interaction between the scalar and the SM can be taken almost as high as the Planck scale in the deep UV.