Supersymmetry and neutrinoless double beta decay.

Neutrinoless double beta decay (0νββ) induced by superparticle exchange is investigated. Such a supersymmetric (SUSY) mechanism of 0νββ decay arises within SUSY theories with R-parity non-conservation (R p /). We consider the minimal supersymmetric standard model (MSSM) with explicit R p / terms in the superpotential (R p / MSSM). The decay rate for the SUSY mechanism of 0νββ decay is calculated. Numerical values for nuclear matrix elements for the experimentally most interesting isotopes are calculated within pn-QRPA. Constraints on the R p / MSSM parameter space are extracted from current experimental half-life limits. The most stringent limits are derived from data on 76 Ge. It is shown that these constraints are more stringent than those from other low-energy processes and are competitive to or even more stringent than constraints expected from accelerator searches.