Axion dark matter in a $3-3-1$ model

TL;DR

This paper extends a $3-3-1$ model to incorporate axion dark matter, solving the strong CP problem and matching observed dark matter density with axions of about meV mass, potentially detectable by IAXO.

Contribution

It introduces a $3-3-1$ scalar singlet to implement a gravity-stable Peccei-Quinn mechanism within this model, addressing dark matter and strong CP problem simultaneously.

Findings

Axions with masses around meV can account for the total dark matter relic density.

The model's parameter space allows axions to be detected by IAXO.

The approach provides a unified solution to dark matter and the strong CP problem.

Abstract

Slightly extending a right-handed neutrino version of the $3-3-1$ model, we show that it is not only possible to solve the strong CP problem but also to give the total dark matter abundance reported by the Planck collaboration. Specifically, we consider the possibility of introducing a $3-3-1$ scalar singlet to implement a gravity stable Peccei-Quinn mechanism in this model. Remarkably, for allowed regions of the parameter space, the arising axions with masses $m_a\approx$ meV can both make up the total dark matter relic density through non-thermal production mechanisms and be very close to the region to be explored by the IAXO helioscope.