Search for neutrinoless double-beta decay of Mo 100 with the NEMO-3 detector

We report the results of a search for the neutrinoless double-s decay (0?ss ) of Mo 100 , using the NEMO-3 detector to reconstruct the full topology of the final state events. With an exposure of 34.7??kg·y , no evidence for the 0?ss signal has been found, yielding a limit for the light Majorana neutrino mass mechanism of T 1/2 (0?ss)>1.1×10 24 years (90% C.L.) once both statistical and systematic uncertainties are taken into account. Depending on the nuclear matrix elements this corresponds to an upper limit on the Majorana effective neutrino mass of ?m ? ?<0.3–0.9??eV (90% C.L.). Constraints on other lepton number violating mechanisms of 0?ss decays are also given. Searching for high-energy double electron events in all suitable sources of the detector, no event in the energy region [3.2–10] MeV is observed for an exposure of 47??kg·y .