When Freeze-out Precedes Freeze-in: Sub-TeV Fermion Triplet Dark Matter with Radiative Neutrino Mass

TL;DR

This paper introduces a hybrid dark matter production model combining thermal freeze-out and non-thermal freeze-in mechanisms, linked with radiative neutrino mass generation, and explores its testable collider and detection signatures.

Contribution

It presents a minimal model where dark matter relic abundance arises from both freeze-out and freeze-in, connecting it with radiative neutrino mass and collider phenomenology.

Findings

Dark matter under-abundant from freeze-out in sub-TeV range

Late decay of scalar doublet enables freeze-in contribution

Model predicts disappearing charge tracks and detectable signals

Abstract

We propose a minimal predictive scenario for dark matter and radiative neutrino mass where the relic abundance of dark matter is generated from a hybrid setup comprising of both thermal freeze-out as well as non-thermal freeze-in mechanisms. Considering three copies of fermion triplets and one scalar doublet, odd under an unbroken $\mathbb{Z}_2$ symmetry, to be responsible for radiative origin of neutrino mass, we consider the lightest fermion triplet as a dark matter candidate which remains under-abundant in the sub-TeV regime from usual thermal freeze-out. Late decay of the $\mathbb{Z}_2$-odd scalar doublet into dark matter serves as the non-thermal (freeze-in) contribution which not only fills the thermal dark matter deficit, but also constrains the mother particle's parameter space so that the correct relic abundance of dark matter is generated. Apart from showing interesting differences from the purely freeze-out and purely freeze-in dark matter scenarios, the model remains testable through disappearing charge track signatures at colliders, observable direct and indirect detection rates for dark matter and prediction of almost vanishing lightest neutrino mass.