Neutrino Masses and Hubble Tension via a Majoron in MFV

TL;DR

This paper proposes a particle physics model involving a Majoron that addresses the Hubble tension and explains neutrino masses within a minimal flavor violation framework, also incorporating a QCD axion.

Contribution

It introduces a novel mechanism linking Majoron dynamics to the Hubble tension and neutrino mass generation in a minimal flavor violation context.

Findings

Majoron can alleviate Hubble tension

Model explains active neutrino masses

Constraints from heavy neutrino decays and Higgs decays

Abstract

The recent tension between local and early measurements of the Hubble constant can be explained in a particle physics context. A mechanism is presented where this tension is alleviated due to the presence of a Majoron, arising from the spontaneous breaking of Lepton Number. The lightness of the active neutrinos is consistently explained. Moreover, this mechanism is shown to be embeddable in the Minimal (Lepton) Flavour Violating context, providing a correct description of fermion masses and mixings, and protecting the flavour sector from large deviations from the Standard Model predictions. A QCD axion is also present to solve the Strong CP problem. The Lepton Number and the Peccei-Quinn symmetries naturally arise in the Minimal (Lepton) Flavour Violating setup and their spontaneous breaking is due to the presence of two extra scalar singlets. The Majoron phenomenology is also studied in detail. Decays of the heavy neutrinos and the invisible Higgs decay provide the strongest constraints in the model parameter space.