Detailed studies of 100 Mo two-neutrino double beta decay in NEMO-3

Abstract

The full data set of the NEMO-3 experiment has been used to measure the half-life of the two-neutrino double beta decay of 100Mo to the ground state of 100Ru, T1/2=[6.81±0.01(stat)-0.40+0.38(syst)]×1018 year. The two-electron energy sum, single electron energy spectra and distribution of the angle between the electrons are presented with an unprecedented statistics of 5 × 10 5 events and a signal-to-background ratio of ∼ 80. Clear evidence for the Single State Dominance model is found for this nuclear transition. Limits on Majoron emitting neutrinoless double beta decay modes with spectral indices of n = 2 , 3 , 7 , as well as constraints on Lorentz invariance violation and on the bosonic neutrino contribution to the two-neutrino double beta decay mode are obtained.