Dirac neutrinos from Peccei-Quinn symmetry: Two examples

Leon M.G De La Vega,Newton Nath,Eduardo Peinado

doi:10.1016/j.nuclphysb.2020.115099

Leon M.G De La Vega, Newton Nath + Show 1 more

Open Access

https://doi.org/10.1016/j.nuclphysb.2020.115099

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Abstract

We aim to explain the nature of neutrinos using Peccei-Quinn symmetry. We discuss two simple scenarios, one based on a type-II Dirac seesaw and the other in a one-loop neutrino mass generation, which solve the strong CP problem and naturally lead to Dirac neutrinos. In the first setup latest neutrino mass limit gives rise to axion which is in the reach of conventional searches. Moreover, we have both axion as well as WIMP dark mater for our second set up.

Highlights

Over the past few decades there has been remarkable progress in the field of particle physics
We extend the idea by using a type-II seesaw with exactly the same PQ charges for the RH neutrino and by including an extra Higgs doublet to give the small Dirac neutrino masses
We propose two different scenarios to generate naturally small effective Yukawa coupling for neutrinos

Summary

INTRODUCTION

Over the past few decades there has been remarkable progress in the field of particle physics. The PQ symmetry predicts the existence of the associated pseudo-Nambu-Goldstone (pNG) boson, the axion [5, 6] which can be a good cold dark matter candidate [7,8,9,10] Another puzzling challenge in the neutrino sector is whether neutrinos are Dirac or Majorana particles. It is worthwhile to point out here that they have considered quartic coupling which is responsible to generate the Dirac neutrino masses, whereas our focus is on trilinear coupling to explain the same within the type - II seesaw model. [34] has discussed the generation of the Dirac neutrino mass at one-loop level within the framework of scotogenic model in the context of KSVZ [15, 16] In both the cases the Diracness of neutrinos is guaranteed by Lepton number itself and not by the PQ symmetry as pointed out here. In both frameworks, we show how it leads to a novel class of minimal axion models that effectively imply Dirac neutrinos

FRAMEWORK

Case-I

Case-II

SUMMARY