Reloading the Axion in a 3-3-1 setup

TL;DR

This paper extends the axion concept within an SU(3)_L x U(1)_X gauge symmetry, proposing a minimal model that addresses the strong-CP problem, neutrino masses, and predicts distinctive axion couplings.

Contribution

It introduces a minimal axion extension of the SVS model with novel axion-photon and flavor-changing couplings, integrating neutrino mass generation.

Findings

Enhanced axion-photon coupling compared to DFSZ

Flavor-changing axion-quark interactions

Neutrino masses from Dirac seesaw mechanism

Abstract

We generalize the idea of the axion to an extended electroweak gauge symmetry setup. We propose a minimal axion extension of the Singer-Valle-Schechter (SVS) theory, in which the standard model fits in $\mathrm{SU(3)_L\otimes U(1)_X}$, the number of families results from anomaly cancellation, and the Peccei-Quinn (PQ) solution to the strong-CP problem is implemented. Neutrino masses arise from a type-I Dirac seesaw mechanism, suppressed by the ratio of SVS and PQ scales, suggesting the existence of new physics at a moderate SVS scale. Novel features include an enhanced axion coupling to photons when compared to the DFSZ axion, as well as flavour-changing axion couplings to quarks.