Ver artículo

The orders of magnitude of decay rates for relatively light neutrinos are studied in the framework of the SU (2)× U (1) gauge group. The assumption is made that a hierarchy parameter ε (≈(muon mass)÷[some new mass scale (possibly much smaller than the grand unification scale)]) plays a meaningful role in the full theory. For orientation it is first noted that the traditional ν γ decay channel as well as the 3 ν decay channel give neutrino lifetimes which for" typical" parameters are substantially longer than the age of the universe. Then we examine in detail some recent proposals which are claimed to result in greatly speeded-up decays into ν+ Majoron, where the Majoron is a true Goldstone boson associated with spontaneous breakdown of lepton number. In a theory in which the usual Higgs doublet is augmented by a complex singlet (1-2 model) it is noted that the decay width into ν+ Majoron actually vanishes to …