The CUPID-Mo experiment to search for 0$$\nu \beta \beta $$
ν
β
β
decay in $$^{100}$$
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 0$$\nu \beta \beta $$
ν
β
β
decay experiment. CUPID-Mo was comprised of 20 enriched $$\hbox {Li}_{{2}}$$
Li
2
$$^{100}$$
100
$$\hbox {MoO}_4$$
MoO
4
scintillating calorimeters, each with a mass of $$\sim 0.2$$
∼
0.2
kg, operated at $$\sim 20$$
∼
20
mK. We present here the final analysis with the full exposure of CUPID-Mo ($$^{100}$$
100
Mo exposure of 1.47 $$\hbox {kg} \times \hbox {year}$$
kg
×
year
) used to search for lepton number violation via 0$$\nu \beta \beta $$
ν
β
β
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 $$^{100}$$
100
Mo 0$$\nu \beta \beta $$
ν
β
β
decay half-life of $$T_{1/2}^{0\nu }$$
T
1
/
2
0
ν
$$> {1.8}\times 10^{24}$$
>
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 $$\left<m_{\beta \beta }\right>$$
m
β
β
$$<~{(0.28{-}0.49)} $$
<
(
0.28
-
0.49
)
eV, dependent upon the nuclear matrix element utilized.