Improved Limit on Neutrinoless Double-Beta Decay in 130Te with CUORE

We report new results from the search for neutrinoless double-beta decay in ¹³⁰Te with the CUORE detector. This search benefits from a fourfold increase in exposure, lower trigger thresholds, and analysis improvements relative to our previous results. We observe a background of (1.38 ±0.07 )×10^-2 counts /(keV kg yr ) ) in the 0 ν β β decay region of interest and, with a total exposure of 372.5 kg yr, we attain a median exclusion sensitivity of 1.7 ×10²⁵ yr . We find no evidence for 0 ν β β decay and set a 90% credibility interval Bayesian lower limit of 3.2 ×10²⁵ yr on the ¹³⁰Te half-life for this process. In the hypothesis that 0 ν β β decay is mediated by light Majorana neutrinos, this results in an upper limit on the effective Majorana mass of 75-350 meV, depending on the nuclear matrix elements used.