PHENOMENOLOGICAL CONSEQUENCES OF SINGLET NEUTRINOS

In this paper, we study the phenomenology of right-handed neutrino iso singlets. We consider the general situation where the neutrino masses are not necessarily given by m(D)2/M, where m(D) and M are the Dirac a nd Majorana mass terms, respectively. The consequent mixing between th e light and heavy neutrinos is then not suppressed, and we treat it as an independent parameter in the analysis. It turns out that mu-e conv ersion is an important experiment in placing limits on the heavy mass scale (M) and the mixing. Mixings among light neutrinos are constraine d by neutrinoless double-beta decay, as well as by solar and atmospher ic neutrino experiments. Detailed one-loop calculations for lepton-num ber-violating vertices are provided.