From Peccei Quinn symmetry to mass hierarchy problem

TL;DR

This paper introduces a novel gauge extension and global symmetry to address the fermion mass hierarchy and strong CP problem, proposing a model with axions as dark matter candidates and neutrino mass generation.

Contribution

It presents a new non-universal U(1)_X gauge extension combined with a Peccei-Quinn symmetry, explaining fermion masses, neutrino masses, and dark matter within a unified framework.

Findings

Fermion mass spectrum generated through symmetry breaking

Neutrino masses explained via see-saw mechanism

Axion as a Cold Dark Matter candidate

Abstract

We propose a non-universal $\mathrm{U}(1)_{X}$ gauge extension to the Standard Model (SM) and an additional Peccei-Quinn (PQ) global symmetry to study the mass hierarchy and strong CP problem. The scheme allows us to distinguish among fermion families and to generate the fermionic mass spectrum of particles of the SM. The symmetry breaking is performed by two scalar Higgs doublets and two scalar Higgs singlets, where one of these has the axion which turns out to be a candidate for Cold Dark Matter. The exotic sector is composed by one up-like $T$ and two down-like $J^{1,2}$ heavy quarks, two heavy charged leptons $E,\mathcal{E}$, one additional right-handed neutrino per family $\nu_{R}^{e,\mu,\tau}$, and an invisible axion $a$. In addition, the large energy scale associated to the breaking of the PQ-symmetry gives masses to the right-handed neutrinos in such a way that the active neutrinos acquire eV-mass values due to the see-saw mechanism. On the other hand, from the non-linear effective Lagrangian, the flavour changing of the down quarks and charged leptons with the axion are considered.