On the SUSY Accompanied Neutrino Exchange Mechanism of Neutrinoless Double Beta Decay

The neutrinoless double beta decay ($\znbb$) induced by light Majorana neutrino exchange between decaying nucleons, accompanied by the squark exchange inside one nucleon, recently discussed by Babu and Mohapatra, is carefully analyzed both from the particle and nuclear physics sides. New nuclear matrix elements relevant to this mechanism are calculated. We extend the analysis to include mixing of light neutrinos with heavy and "sterile" neutrinos. It introduces another supersymmetric (SUSY) contribution to $\znbb$. We discuss constraints on the \rp MSSM parameters imposed by the current experimental limit on $\znbb$ decay half-life of $^{76}$Ge.