Some comments on decaying neutrinos and the triplet majoron model

We investigate in the framework of the triplet majoron model various additional physical manifestations which should occur if the recent suggestion of Bahcall, Petcov, Toshev and Valle that the electron neutrino decays into the muon neutrino and a majoron en route from the sun is indeed correct. We find no observable manifestation which could rule out this suggestion. Furthermore we show that the parameter chosen to make the decay lifetime of B⁸ neutrinos comparable with 500 s, the sun-earth transit time, is natural at least in the sense that much (100-1000 times) shorter life times can be ruled out. We observe that only decays ν_e → ν_μ+X⁰, where the unobservable X⁰ carries two units of lepton number, avoid prohibitively large (> 99% branching) μ→e+X⁰ transitions. This selects uniquely the triplet majoron model - or variants thereof - as the theoretical framework for decaying neutrinos.