Singlet fermion dark matter and Dirac neutrinos from Peccei-Quinn symmetry

TL;DR

This paper proposes a unified model linking the Peccei-Quinn symmetry to solving the strong CP problem, generating Dirac neutrino masses, and explaining multicomponent dark matter, with testable predictions for future experiments.

Contribution

It introduces a novel model where PQ symmetry simultaneously addresses multiple open questions in particle physics and cosmology, including neutrino masses and dark matter.

Findings

Model can be tested in future WIMP and axion searches.

Predicts rates for rare leptonic decays within upcoming experimental sensitivity.

Compatible with current neutrino oscillation and dark matter constraints.

Abstract

The Peccei-Quinn (PQ) mechanism not only acts as an explanation for the absence of strong CP violation but also can play a main role in the solution to other open questions in particle physics and cosmology. Here we consider a model that identifies the PQ symmetry as a common thread in the solution to the strong CP problem, the generation of radiative Dirac neutrino masses and the origin of a multicomponent dark sector. Specifically, scotogenic neutrino masses arise at one loop level with the lightest fermionic mediator field acting as the second dark matter (DM) candidate thanks to the residual $Z_2$ symmetry resulting from the PQ symmetry breaking. We perform a phenomenological analysis addressing the constraints coming from the direct searches of DM, neutrino oscillation data and charged lepton flavor violating (LFV) processes. We find that the model can be partially probed in future facilities searching for WIMPs and axions, and accommodates rates for rare leptonic decays that are within the expected sensitivity of upcoming LFV experiments.