Spontaneous breaking of a global symmetry in a 331 model

TL;DR

This paper explores a 331 model where spontaneous global symmetry breaking produces a majoron-like Goldstone boson that interacts minimally with standard particles, potentially aligning with experimental constraints and neutrino decay observations.

Contribution

It demonstrates the spontaneous breaking of a global symmetry in a 331 model, resulting in a unique, non-mixing majoron with specific interaction properties and cosmological viability.

Findings

Majoron does not mix with other scalars and does not couple to charged leptons or quarks at tree level.

Model parameters can satisfy the invisible Z^0-width constraints.

Heavy neutrinos can decay rapidly via majoron emission, shorter than the universe's age.

Abstract

In a 331 model in which the lepton masses arise from a scalar sextet it is possible to break spontaneously a global symmetry implying in a pseudoscalar majoron-like Goldstone boson. This majoron does not mix with any other scalar fields and for this reason it does not couple, at the tree level, neither to the charged leptons nor to the quarks. Moreover, its interaction with neutrinos is diagonal. We also argue that there is a set of the parameters in which that the model can be consistent with the invisible Z^0-width and that heavy neutrinos can decay sufficiently rapid by majoron emission having a lifetime shorter than the age of the universe.