# One-loop Dirac neutrino mass and mixed axion/WIMP dark matter

## TL;DR

This paper proposes a model where the Peccei-Quinn symmetry explains Dirac neutrino masses generated at one loop, and predicts a mixed dark matter scenario involving axions and WIMPs stabilized by residual symmetries.

## Contribution

It introduces a novel mechanism linking PQ symmetry to one-loop Dirac neutrino mass generation and dark matter stabilization.

## Key findings

- Neutrino masses arise predominantly from one-loop diagrams due to PQ symmetry.
- The model predicts stable mediators forming a dark sector with axion/WIMP dark matter.
- Residual symmetries from PQ breaking stabilize dark matter candidates.

## Abstract

We consider the Peccei-Quinn (PQ) mechanism as the one behind the Dirac neutrino masses when these are generated through the $d=5$ effective operator $\bar{L}\tilde{H}N_R\phi$ at one loop level, with $\phi$ being a Standard Model singlet scalar. In this setup, the PQ symmetry guarantees that the one-loop realization of such an effective operator gives the leading contribution to the Dirac neutrino masses by forbidding the contributions arising from its tree level realizations. All the mediators in the one-loop neutrino mass diagrams can be stabilized by a remnant $Z_N$ symmetry from the PQ symmetry breaking, thus forming a dark sector besides the axion sector and leading to mixed axion/WIMP dark matter scenarios.