New Limit for Neutrinoless Double-Beta Decay of $^{100}$Mo from the CUPID-Mo Experiment

TL;DR

The CUPID-Mo experiment sets a new lower limit on the half-life of neutrinoless double-beta decay in $^{100}$Mo, constraining the effective Majorana neutrino mass to below 0.54 eV, with no observed decay events after over a year of data collection.

Contribution

This work provides the first experimental limit on $^{100}$Mo neutrinoless double-beta decay using cryogenic scintillating bolometers, advancing the search for lepton number violation.

Findings

No decay events observed in the region of interest.

Established a new half-life lower limit of $1.5 imes 10^{24}$ years.

Constrained the effective Majorana neutrino mass to below 0.54 eV.

Abstract

The CUPID-Mo experiment at the Laboratoire Souterrain de Modane (France) is a demonstrator for CUPID, the next-generation ton-scale cryogenic $0\nu\beta\beta$ experiment. It consists of a 4.2 kg array of 20 enriched Li$_{2}$$^{100}$MoO$_4$ scintillating bolometers to search for the lepton number violating process of $0\nu\beta\beta$ decay in $^{100}$Mo. With more than one year of operation (2.16 kg$\times$yr of physics data), no event in the region of interest and hence no evidence for $0\nu\beta\beta$ is observed. We report a new limit on the half-life of $0\nu\beta\beta$ decay in $^{100}$Mo of $T_{1/2} > 1.5 \times 10^{24}\,$yr at 90 % C.I. The limit corresponds to an effective Majorana neutrino mass $\langle m_{\beta\beta} \rangle$ $<$ (0.31--0.54)$\,$eV, dependent on the nuclear matrix element in the light Majorana neutrino exchange interpretation.