Axionic Dirac seesaw and electroweak vacuum stability

TL;DR

This paper links axion physics with Dirac neutrino masses via a PQ symmetry, proposing a model that stabilizes the electroweak vacuum and potentially explains recent anomalies in W boson mass measurements.

Contribution

It introduces a KSVZ-type model connecting axion scale to Dirac neutrino masses with an added scalar triplet, analyzing its impact on vacuum stability and W mass.

Findings

Neutrino masses inversely proportional to PQ scale

Scalar triplet stabilizes electroweak vacuum

Possible explanation for CDF W mass anomaly

Abstract

We explore the connection between tree-level Dirac neutrino masses and axion physics in a scenario where the PQ symmetry enforces lepton number conservation perturbatively. Requiring that the PQ scale $f_a$ is the only heavy scale to play a role in neutrino mass generation, we are led to the construction of a KSVZ-type model where Dirac neutrino masses are inversely proportional to $f_a$, provided a real scalar triplet (zero hypercharge) is added to the SM scalar sector. We analyse this extended scalar sector, focusing on the stabilisation of the electroweak vacuum. The contribution of the triplet VEV to the $W$ mass may also be responsible for the recent hint of beyond-the-SM physics by the CDF collaboration.