Clockwork origin of neutrino mixings

Teruyuki Kitabayashi

doi:10.1103/physrevd.100.035019

Abstract

The clockwork mechanism provides a natural way to obtain hierarchical masses and couplings in a theory. We propose a clockwork model that has nine clockwork generations. In this model, the candidates of the origin of the neutrino mixings are nine Yukawa mass matrix elements $Y^{a\beta}$ that connect neutrinos and clockwork fermions, nine clockwork mass ratios $q_{a\beta}$, and nine numbers of clockwork fermions $n_{a\beta}$, where $a, \beta=1,2,3$. Assuming $|Y^{a\beta}|=1$, the neutrino mixings originate from the pure clockwork sector. We show that the observed neutrino mixings are exactly obtained from a clockwork model in the case of the $q_{a\beta}$ origin scenario. In the $n_{a\beta}$ origin scenario, the correct order of magnitude of the observed neutrino mixings is obtained from a clockwork model.

Highlights

One of the outstanding problems in particle physics is the origin of the neutrino masses and mixings [1]
We extend the clockwork model proposed by Ibarra et al [48] to propose a clockwork model that has nine clockwork generations
We have proposed a clockwork model that has nine clockwork generations

Summary

INTRODUCTION

One of the outstanding problems in particle physics is the origin of the neutrino masses and mixings [1]. The clockwork mechanism provides a new natural way to obtain hierarchical masses and couplings in a theory. [48] by Ibarra et al In this model, the neutrino mass maνβ is obtained as maνβ 1⁄4 fðYaβ; qβ; nβÞ; ð2Þ where a 1⁄4 1, 2, 3 and β ≥ 2 for observed three neutrino generations, Yaβ denotes the Yukawa coupling (which connects the standard model sector to the clockwork sector), qβ is the clockwork mass ratio, and nβ is number of clockwork fields in the βth clockwork generation. We will show that a model with the democratic Yukawa matrix jYaβj 1⁄4 1 is consistent with the observed neutrino masses and mixings In this case, the mixings of the neutrinos originate from the clockwork fields instead of the Yukawa couplings.

Observed neutrino masses and mixings

Fermionic clockwork mechanism

ORIGIN OF NEUTRINO MIXINGS

Effective naβ with universal q

Inverted mass ordering

SUMMARY