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-beta decay of Nd-150 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 Nd-150, we measured the half-life for 2 nu beta beta decay to be T-1/2(2 nu) = (9.11(-0.22)(+0.25)(stat.) +/- 0.63(syst.)) x 10(18) yr. The observed limit on the half-life for neutrinoless double-beta decay is found to be T-1/2(0 nu) > 1.8 x 10(22) yr at 90% confidence level. This translates into a limit on the effective Majorana neutrino mass of < m(nu)> < 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.