A $U(1)_{X}$ extension to the SM with three families and Peccei Quinn symmetry

TL;DR

This paper introduces a non-universal $U(1)_X$ extension of the Standard Model with three families and a Peccei-Quinn symmetry, addressing fermion mass hierarchies, the strong CP problem, and neutrino masses.

Contribution

It proposes a novel $U(1)_X$ extension with a global PQ symmetry that explains fermion hierarchies, solves the strong CP problem, and generates neutrino masses via the see-saw mechanism.

Findings

Provides a mechanism for fermion mass hierarchy

Offers a solution to the strong CP problem with an axion

Generates neutrino masses consistent with observations

Abstract

We propose a non-universal $U(1)_{X}$ extension to the Standard Model with three families and an additional global anomala Peccei-Quinn (PQ) symmetry. The breaking of the former allows us to give masses to the exotic fermionic sector and the later generates the necessary zeros in the mass matrices to explain the fermionic mass hierarchy. In addition, the large energy scale associated with the spontaneously breaking (SSB) of the PQ symmetry provides a solution to the strong CP-problem and an axion that could be a possible dark matter candidate. Also, the SSB allows to generate right-handed neutrino masses, so the active neutrinos acquire $eV$-mass values due to the see-saw mechanism implementation.