Final results on the 0nu beta beta decay half-life limit of ^{100}Mo from the CUPID-Mo experiment

Abstract

The CUPID-Mo experiment to search for 0nu beta beta decay in ^{100}Mo has been recently completed after about 1.5 years of operation at Laboratoire Souterrain de Modane (France). It served as a demonstrator for CUPID, a next generation 0nu beta beta decay experiment. CUPID-Mo was comprised of 20 enriched hbox {Li}_{{2}}^{100}hbox {MoO}_4 scintillating calorimeters, each with a mass of sim 0.2 kg, operated at sim 20 mK. We present here the final analysis with the full exposure of CUPID-Mo (^{100}Mo exposure of 1.47 hbox {kg} times hbox {year}) used to search for lepton number violation via 0nu beta beta decay. We report on various analysis improvements since the previous result on a subset of data, reprocessing all data with these new techniques. We observe zero events in the region of interest and set a new limit on the ^{100}Mo 0nu beta beta decay half-life of T_{1/2}^{0nu }> {1.8}times 10^{24} year (stat. + syst.) at 90% CI. Under the light Majorana neutrino exchange mechanism this corresponds to an effective Majorana neutrino mass of left<m_{beta beta }right>  <~{(0.28{-}0.49)}  eV, dependent upon the nuclear matrix element utilized.