Radiative symmetry breaking in a gauged Zee-Babu model and its gravitational wave imprints

TL;DR

This paper presents a scale-invariant gauged Zee-Babu model with $U(1)_{B-L}$ symmetry, where radiative symmetry breaking leads to neutrino masses, dark matter, and detectable gravitational wave signals from early universe phase transitions.

Contribution

It introduces a novel classically scale-invariant model linking neutrino mass, dark matter, and gravitational wave predictions through radiative symmetry breaking.

Findings

Achieves neutrino masses and mixings consistent with observations.

Predicts gravitational waves detectable by LISA and BBO.

Identifies a viable $v_{BL}$ range for dark matter and lepton flavor violation.

Abstract

We construct a classically scale invariant version of the Zee-Babu model governed by an $U(1)_{B-L}$ gauge symmetry wherein three right handed neutrinos with identical gauge charges are present. A $\mathbb{Z}_2$ symmetry is additionally imposed such that the lightest right handed neutrino becomes a dark matter candidate. A spontaneous breakdown of the $U(1)_{B-L}$ gauge group is triggered radiatively through renormalisation group effects and the dimensionful parameters thus emerging are proportional to the corresponding breaking scale $v_{BL}$. We demonstrate in this study how the same $v_{BL}$ controls the dynamics of neutrino mass generation, lepton flavour violation and dark matter phenomenology. It is revealed that the scenario can simultaneously accommodate the observed neutrino masses and mixings, an appropriately low lepton flavour violation and the observed dark matter relic density for 10 TeV $\lesssim v_{BL} \lesssim$ 55 TeV. In addition, the very radiative nature of the set-up signals a strong first order phase transition in the presence of a non-zero temperature. Stochastic gravitational waves stemming from this phase transition are within the reach of detectors such as LISA and BBO. The scenario therefore emerges as a concrete platform to test classical scale invariance that is tied to neutrino masses and dark matter, through gravitational waves.