Measurement of the double-β decay half-life of 150Nd and search for neutrinoless decay modes with the NEMO-3 detector

The half-life for double-β decay of 150Nd has been measured by the NEMO-3 experiment at the Modane Underground Laboratory. Using 924.7 days of data recorded with 36.55 g of 150Nd, we measured the half-life for 2νββ decay to be T1/22ν=(9.11-0.22+0.25(stat.)±0.63(syst.))x1018 yr. The observed limit on the half-life for neutrinoless double-β decay is found to be T1/20ν>1.8x1022 yr at 90% confidence level. This translates into a limit on the effective Majorana neutrino mass of <4.0-6.3 eV if the nuclear deformation is taken into account. We also set limits on models involving Majoron emission, right-handed currents, and transitions to excited states.