Loop-Induced Majoronic Decay of Neutrinos:

Abstract

In models where the suppression of the tree level couplings of fermions with Goldstone bosons is not protected by symmetry, the loop-induced couplings can in general dominate over the tree couplings. We demonstrate this by calculating the decay $ν\to ν' + \mbox{Majoron}$ in the simplest singlet Majoron model. It is shown that 1-loop contributions can be orders of magnitude bigger than the tree-level result, and hence allows a wide range of interesting values of neutrino mass and mixing to be compatible with cosmological constraints.

(7 pages LATEX) 5 pages of figures can be sent on request. [NUHEP-TH-93-17, UPR-0576T, DOE-ER40757-019, CPP-93-19]