Loop-induced Neutrino Masses: A Case Study

TL;DR

This paper analyzes a three-loop neutrino mass generation model involving dark matter particles, providing detailed calculations and exploring parameter space consistent with experimental constraints.

Contribution

It offers the first complete analytic expressions for neutrino masses in the cocktail model and performs a comprehensive numerical analysis of the parameter space.

Findings

Large couplings are necessary for the model.

A significant mass difference between scalars is required.

Parameter space consistent with experimental constraints is identified.

Abstract

We study the cocktail model in which the Majorana neutrino masses are generated by the so-called "cocktail" three-loop diagrams with the dark matter particle running in the loops. In particular, we give the correct analytic expressions of the neutrino masses in the model by the detailed calculation of the cocktail diagrams. Based on the reliable numerical calculation of the loop integrals, we explore the parameter space which can give the correct orders of neutrino masses while satisfying other experimental constraints, such as those from the neutrinoless double beta decay, low-energy lepton flavor violation processes, electroweak precision tests, and collider searches. As a result, the large couplings and the large mass difference between the two singly-charged (neutral) scalars are required.