Neutrinos, Axions and Conformal Symmetry

TL;DR

This paper explores how conformal symmetry breaking in an extended Standard Model naturally produces an axion-like particle linked to neutrino masses, with couplings determined by anomalies.

Contribution

It introduces a mechanism where conformal symmetry breaking induces lepton number breaking, leading to a calculable axion-like particle with unique properties.

Findings

Axion-like particle couples to photons and gluons via conformal anomaly.

Couplings are small and related to light neutrino masses.

Provides a new link between neutrino physics and axion phenomenology.

Abstract

We demonstrate that radiative breaking of conformal symmetry (and simultaneously electroweak symmetry) in the Standard Model with right-chiral neutrinos and a minimally enlarged scalar sector induces spontaneous breaking of lepton number symmetry, which naturally gives rise to an axion-like particle with some unusual features. The couplings of this `axion' to Standard Model particles, in particular photons and gluons, are entirely determined (and computable) via the conformal anomaly, and their smallness turns out to be directly related to the smallness of the masses of light neutrinos.