Search for Neutrinoless Quadruple- β Decay of Nd150 with the NEMO-3 Detector

We report the results of a first experimental search for lepton number violation by four units in the neutrinoless quadruple-β decay of Nd150 using a total exposure of 0.19 kg yr recorded with the NEMO-3 detector at the Modane Underground Laboratory. We find no evidence of this decay and set lower limits on the half-life in the range T1/2>(1.1–3.2)×1021 yr at the 90% C.L., depending on the model used for the kinematic distributions of the emitted electrons.