Mixed Inert Scalar Triplet Dark Matter, Radiative Neutrino Masses and Leptogenesis

TL;DR

This paper explores a mixed inert scalar triplet model for dark matter, neutrino mass generation, and leptogenesis, analyzing parameter space constraints and the interplay of gauge and scalar interactions.

Contribution

It introduces a novel mixed inert scalar triplet framework that links dark matter stability, neutrino masses, and baryon asymmetry within a unified model.

Findings

Allowed parameter space consistent with relic abundance and detection limits.

Heavy inert fermions can generate neutrino masses at one-loop level.

Model can successfully explain baryon asymmetry via leptogenesis.

Abstract

The neutral component of an inert scalar multiplet with hypercharge can provide a stable dark matter particle when its real and imaginary parts have a splitting mass spectrum. Otherwise, a tree-level dark matter-nucleon scattering mediated by the $Z$ boson will be much above the experimental limit. In this paper we focus on a mixed inert scalar triplet dark matter scenario where a complex scalar triplet with hypercharge can mix with another real scalar triplet without hypercharge through their renormalizable coupling to the standard model Higgs doublet. We consider three specified cases that carry most of the relevant features of the full parameter space: (i) the neutral component of the real triplet dominates the dark matter particle, (ii) the neutral component of the complex triplet dominates the dark matter particle; and (iii) the neutral components of the real and complex triplets equally constitute the dark matter particle. Subject to the dark matter relic abundance and direct detection constraint, we perform a systematic study on the allowed parameter space with particular emphasis on the interplay among triplet-doublet terms and gauge interactions. In the presence of these mixed inert scalar triplets, some heavy Dirac fermions composed of inert fermion doublets can be utilized to generate a tiny Majorana neutrino mass term at one-loop level and realize a successful leptogenesis for explaining the cosmic baryon asymmetry.