Critique of Fermionic R\nuMDM and its Scalar Variants

TL;DR

This paper critically examines the stability of fermionic and scalar minimal dark matter candidates within radiative neutrino mass models, revealing symmetry violations and instability issues that challenge their viability.

Contribution

It identifies a previously overlooked renormalizable term that breaks Z_2 symmetry in fermionic RνMDM models and shows scalar variants are generally unstable due to super-renormalizable terms.

Findings

The fermionic RνMDM quintuplet is destabilized by an additional renormalizable term.

Scalar RνMDM variants are typically unstable because of super-renormalizable terms in the potential.

The claimed accidental Z_2 symmetry does not ensure dark matter stability in these models.

Abstract

We examine the stability of minimal dark matter (MDM) particle-candidates in the setup in which they participate in radiative neutrino (R\nu) masses. We first point out the existence of an additional renormalizable term in recently proposed R\nuMDM Lagrangian, which violates the claimed accidental Z_2 symmetry and spoils the stability of the fermionic MDM quintuplet component. We then explore the viability of R$\nu$MDM variants based on scalar MDM multiplets. There are ubiquitous super-renormalizable terms in the scalar potential which make these scalar multiplets unstable.