Improved Limit on Neutrinoless Double-Beta Decay in ${}^{130}$Te with CUORE

Abstract

We report new results from the search for neutrinoless double-beta decay in ${}^{130}$Te with the CUORE detector. This search benefits from a four-fold increase in exposure, lower trigger thresholds and analysis improvements relative to our previous results. We observe a background of $(1.38\pm 0.07)\cdot 10^{-2}$ counts$/($keV$\cdot$kg$\cdot$yr$)$ in the $0\hat{I}½{\hat{I}}^2{\hat{I}}^2$ decay region of interest and, with a total exposure of 372.5 kg$\cdot$yr, we attain a median exclusion sensitivity of $1.7\cdot 10^{25}$ yr. We find no evidence for $0\hat{I}½{\hat{I}}^2{\hat{I}}^2$ decay and set a $90\%$ CI Bayesian lower limit of $3.2\cdot 10^{25}$ yr on the ${}^{130}$Te half-life for this process. In the hypothesis that $0\hat{I}½{\hat{I}}^2{\hat{I}}^2$ 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.

7 pages, 5 figures