Supersymmetry and neutrinoless double β decay

Neutrinoless double β decay (0νββ) induced by superparticle exchange is investigated. Such a supersymmetric (SUSY) mechanism of 0νββ decay arises within SUSY theories with R-parity nonconservation (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 the proton-neutron quasiparticle random phase approximation. 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 Ge⁷⁶. It is shown that these constraints are more stringent than those from other low-energy processes and are competitive with or even more stringent than constraints expected from accelerator searches.