Gravitational waves from neutrino mass genesis

TL;DR

This paper explores how primordial gravitational waves could serve as signatures of neutrino mass generation mechanisms, especially through phase transitions in Majoron models, and discusses potential implications for cosmology and dark matter.

Contribution

It proposes that phase transitions in Majoron models can produce detectable gravitational waves linked to neutrino mass generation, connecting particle physics with cosmological observations.

Findings

Primordial gravitational waves could indicate neutrino mass generation mechanisms.

Low-scale phase transitions might be detectable at very low frequencies.

Such physics could help address cosmological tensions like the Hubble tension.

Abstract

The discovery of gravitational waves opens new opportunities to test BSM physics. In particular, the production of a stochastic background of primordial gravitational waves could provide a signature of the generation of the right-right Majorana neutrino mass term necessary, within type-I seesaw mechanism, to explain lightness of neutrinos and their mixing parameters. I will discuss the possibility that such a generation occurs during a strong first order phase transition within Majoron models [1]. As well known, this can indeed produce a stochastic background of gravitational waves. The scale of the phase transition can or cannot coincide with the seesaw scale. In the latter case a low scale phase transition, occurring in the pre-recombination era, might be tested at very low frequencies ($10^{-9}$--$10^{-6}\,{\rm Hz}$). Even though the signal can hardly reproduce the NANOGrac putative signal such new physics at low scale might help ameliorating the tensions in the $\Lambda$CDM cosmological model (e.g., the Hubble tension). I will also discuss how a phase transition might be responsible for the generation of dark matter in the form of dark neutrinos coupling to the seesaw neutrinos via Higgs induced right handed-right handed neutrino mixing [2].