Flavor-changing Majoron interactions with leptons

TL;DR

This paper explores flavor-changing interactions of the Majoron in extended Higgs models, proposing new experimental tests and constraining these interactions using existing data.

Contribution

It introduces the flavor-changing Majoron interactions in the type-III seesaw model and proposes polarization asymmetry as a novel experimental probe.

Findings

Constraints on Majoron couplings from muonium oscillation data

Predictions for polarization asymmetry in lepton decays

Identification of new search channels for Majoron detection

Abstract

When the Standard Model Higgs sector is extended with a complex singlet that breaks global lepton number symmetry spontaneously, a massless Goldstone boson called the Majoron J arises. In addition to increasing Higgs invisible decay through mixing, the Majoron can generally have flavor-changing interactions with fermions. We find that type-III seesaw model poses such interesting properties with both charged leptons and neutrinos. This opens up new channels to search for the Majoron. We use the experimental data such as muonium-anti-muonium oscillation and flavor-changing neutrino and charged lepton decays to put constraints on the couplings. As a novel way to reveal the chiral properties of these interactions, we propose an experimentally measurable polarization asymmetry of flavor-changing l to l' J decays.