Measurement of the ${}^{136}$Xe two-neutrino double beta decay half-life via direct background subtraction in NEXT

Abstract

We report a measurement of the half-life of the ${}^{136}$Xe two-neutrino double beta decay performed with a novel direct background subtraction technique. The analysis relies on the data collected with the NEXT-White detector operated with ${}^{136}$Xe-enriched and ${}^{136}$Xe-depleted xenon, as well as on the topology of double-electron tracks. With a fiducial mass of only 3.5 kg of Xe, a half-life of $2.34_{-0.46}^{+0.80}{\text{(stat)}}_{-0.17}^{+0.30}\text{(sys)}\times 10^{21}\text{yr}$ is derived from the background-subtracted energy spectrum. The presented technique demonstrates the feasibility of unique background-model-independent neutrinoless double beta decay searches.

9 pages, 7 figures, and 1 appendix