An ultraviolet completion for the Scotogenic model

TL;DR

This paper presents an ultraviolet completion of the Scotogenic model, explaining the small neutrino mass parameter naturally and predicting new phenomenology involving a Goldstone boson and additional scalars.

Contribution

It introduces a UV completion that naturally explains the smallness of the $ ext{lambda}_5$ parameter and derives the $ ext{Z}_2$ symmetry from a high-energy global $ ext{U}(1)$ symmetry.

Findings

Provides a UV-complete model with a global U(1) symmetry

Predicts a massless Goldstone boson and additional scalars

Suggests new phenomenological signatures in flavor, dark matter, and collider experiments

Abstract

The Scotogenic model is an economical scenario that generates neutrino masses at the 1-loop level and includes a dark matter candidate. This is achieved by means of an ad-hoc $\mathbb{Z}_2$ symmetry, which forbids the tree-level generation of neutrino masses and stabilizes the lightest $\mathbb{Z}_2$-odd state. Neutrino masses are also suppressed by a quartic coupling, usually denoted by $\lambda_5$. While the smallness of this parameter is natural, it is not explained in the context of the Scotogenic model. We construct an ultraviolet completion of the Scotogenic model that provides a natural explanation for the smallness of the $\lambda_5$ parameter and induces the $\mathbb{Z}_2$ parity as the low-energy remnant of a global $\rm U(1)$ symmetry at high energies. The low-energy spectrum contains, besides the usual Scotogenic states, a massive scalar and a massless Goldstone boson, hence leading to novel phenomenological predictions in flavor observables, dark matter physics and colliders.