We report the results of a first experimental search for lepton number violation by four units in the neutrinoless quadruple-$\beta$ decay of $^{ 150}$Nd using a total exposure of $0.19$ kg$\cdot$y recorded with the NEMO-3 detector at the Modane Underground Laboratory (LSM). We find no evidence of this decay and set lower limits on the half-life in the range $T_{ 1/2}>(1.1-3.2)\times10^{ 21}$ y at the $90\%$ CL, depending on the model used for the kinematic distributions of the emitted electrons.
Categories: hep-ex nucl-ex