Pseudo-Goldstone Neutrinos and Majoron Phenomenology from Spontaneous $U(1){L\mu-L_\tau}$ Breaking

TL;DR

This paper proposes a model where spontaneous breaking of a leptonic symmetry generates neutrino masses, a Majoron-like particle, and pseudo-Goldstone neutrinos, with implications for neutrino physics, cosmology, and collider experiments.

Contribution

It introduces a supersymmetric framework linking leptonic symmetry breaking to neutrino mass generation and phenomenology, including Majoron physics and testable predictions.

Findings

Numerical fit to neutrino oscillation data shows consistency with observations.

Correlation between symmetry breaking scale, neutrino masses, and Majoron couplings.

Potential for future experiments to probe the model's parameter space.

Abstract

We present a predictive framework for neutrino mass generation based on the spontaneous breaking of a leptonic $U(1)_{L_\mu-L_\tau}$ symmetry within a supersymmetric setting. The breaking of the global symmetry gives rise to a Majoron-like axion-like particle and a pseudo-Goldstone right-handed neutrino whose mass is naturally suppressed by supersymmetry-breaking effects. The interplay between the pseudo-Goldstone neutrino and the low-scale seesaw mechanism leads to a structured neutrino mass matrix capable of reproducing the observed neutrino masses, mixing angles, and CP-violating phase without invoking extreme parameter hierarchies. We perform a numerical fit to current neutrino oscillation data and identify representative benchmark solutions consistent with laboratory constraints as well as cosmological and astrophysical bounds. A characteristic outcome of the framework is the emergence of correlated relations linking the symmetry breaking scale, heavy neutrino masses, Majoron couplings, and neutrino lifetimes. Majoron-induced invisible neutrino decay arises generically and can significantly modify cosmological neutrino mass constraints for sufficiently low symmetry breaking scales. We discuss the phenomenological implications across neutrino oscillation experiments, cosmology, and collider searches for long-lived heavy neutrinos. While a detailed experimental simulation is beyond the scope of this work, existing sensitivity projections indicate that portions of the parameter space may become accessible in future facilities. The combined interplay of laboratory probes and cosmological observations provides a consistent and testable picture of neutrino mass generation tied to spontaneous leptonic symmetry breaking and axion-like physics.