A UV Complete Framework of Freeze-in Massive Particle Dark Matter

TL;DR

This paper introduces a UV complete model extending the electroweak symmetry to generate tiny dark matter couplings via loop processes, enabling freeze-in production without fine-tuning, and discusses experimental prospects.

Contribution

It presents a novel UV complete framework for freeze-in dark matter within a left-right symmetric model, utilizing heavy particles as portals through loop couplings.

Findings

Dark matter can be produced via freeze-in with Yukawa couplings of order 0.01 to 1.

The model allows dark matter masses from keV to TeV, compatible with warm and cold dark matter.

The particle sector can be tested at ongoing and future experiments.

Abstract

We propose a way to generate tiny couplings of freeze-in massive particle dark matter with the Standard Model particles dynamically by considering an extension of the electroweak gauge symmetry. The dark matter is considered to be a singlet under this extended gauge symmetry which we have assumed to be the one in a very widely studied scenario called left-right symmetric model. Several heavy particles, that can be thermally inaccessible in the early Universe due to their masses being greater than the reheat temperature after inflation, can play the role of portals between dark matter and Standard Model particles through one loop couplings. Due to the loop suppression, one can generate the required non-thermal dark matter couplings without any need of highly fine tuned Yukawa couplings beyond that of electron Yukawa with the Standard Model like Higgs boson. We show that generic values of Yukawa couplings as large as $\mathcal{O}(0.01)$ to $\mathcal{O}(1)$ can keep the dark matter out of thermal equilibrium in the early Universe and produce the correct relic abundance later through the freeze-in mechanism. Though the radiative couplings of dark matter are tiny as required by the freeze-in scenario, the associated rich particle sector of the model can be probed at ongoing and near future experiments. The allowed values of dark matter mass can remain in a wide range from keV to TeV order keeping the possibilities of warm and cold dark matter equally possible.