Quasi-Dirac fermion: A source of neutrino mass and dark matter

TL;DR

This paper proposes a quasi-Dirac extension of the scotogenic framework to address neutrino masses and dark matter. By introducing an inert doublet $\eta$ and vectorlike fermions $N_{L,R}$ with small lepton-like symmetry-breaking masses $μ_L, μ_R$, neutrino masses are generated radiatively with a suppression proportional to $(μ_L, μ_R)/M$ and loop factors, realizing a radiative inverse-seesaw. The scalar dark matter candidate $A$ achieves the observed relic density via gauge and Higgs portals, while direct detection and LFV constraints constrain couplings such as $h$ and $\lambda_5$. The framework suggests testable predictions for DM mass ranges and mediator properties and can be embedded into broader gauge extensions. Overall, the quasi-Dirac mechanism links neutrino mass generation and dark matter stability in a phenomenologically viable and potentially testable model.

Abstract

Neutral vectorlike fermion as inspired by unified theories might become quasi-Dirac states at TeV due to a violation in lepton-like symmetry. It is shown that such quasi-Dirac fermions can properly achieve radiative neutrino mass generation and dark matter stability. Indeed, the small splitting of quasi-Dirac masses, i.e. $ΔM/M\ll 1$, suitably suppresses neutrino mass to be small in order to allow dark matter annihilation and detection to be appropriate to experiment as well as charged lepton flavor violation limit.

Figures (2)

• Figure 1: Radiative corrections to neutrino mass
• Figure 2: Annihilation processes of $A$'s that set the dark matter abundance.