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arXiv · hep-ph/9307316

A New Class of Majoron-Emitting Double-Beta Decays

C. P. Burgess·J. M. Cline
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Abstract

Motivated by the excess events that have recently been found near the endpoints of the double beta decay spectra of several elements, we re-examine models in which double beta decay can proceed through the neutrinoless emission of massless Nambu-Goldstone bosons (majorons). Noting that models proposed to date for this process must fine-tune either a scalar mass or a VEV to be less than 10 keV, we introduce a new kind of majoron which avoids this difficulty by carrying lepton number $L=-2$. We analyze in detail the requirements that models of both the conventional and our new type must satisfy if they are to account for the observed excess events. We find: (1) the electron sum-energy spectrum can be used to distinguish the two classes of models from one another; (2) the decay rate for the new models depends on different nuclear matrix elements than for ordinary majorons; and (3) all models require a (pseudo) Dirac neutrino, having a mass of a several hundred MeV, which mixes with $ν_e$.

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C. P. Burgess, J. M. Cline. 1993-07-27. A New Class of Majoron-Emitting Double-Beta Decays. https://doi.org/10.1103/physrevd.49.5925

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