Final results on the 0 νββ decay half-life limit of 100 Mo from the CUPID-Mo experiment

The CUPID-Mo experiment to search for 0νββ decay in 100Mo 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 0νββ decay experiment. CUPID-Mo was comprised of 20 enriched Li 2100MoO 4 scintillating calorimeters, each with a mass of ∼ 0.2 kg, operated at ∼ 20 mK. We present here the final analysis with the full exposure of CUPID-Mo (100Mo exposure of 1.47 kg × year) used to search for lepton number violation via 0νββ 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 100Mo 0νββ decay half-life of T1/20ν> 1.8 × 10 24 year (stat. + syst.) at 90% CI. Under the light Majorana neutrino exchange mechanism this corresponds to an effective Majorana neutrino mass of 〈 mββ〉 <(0.28-0.49) eV, dependent upon the nuclear matrix element utilized.