Results from KamLAND-Zen

TL;DR

KamLAND-Zen conducted a preliminary search for neutrinoless double-beta decay in xenon-136, achieving a new lower half-life limit and reducing background noise significantly, with plans for further improvements.

Contribution

This study provides the first combined analysis of pre- and post-purification data, setting a new lower limit on the decay half-life and demonstrating background reduction techniques.

Findings

Lower limit on decay half-life: >2.6 x 10^{25} years

Background reduction by over a factor of 10

Enhanced sensitivity with future upgrades

Abstract

KamLAND-Zen reports on a preliminary search for neutrinoless double-beta decay with ^{136}Xe based on 114.8 live-days after the purification of the xenon loaded liquid scintillator. In this data, the problematic ^{110m}Ag background peak identified in previous searches is reduced by more than a factor of 10. By combining the KamLAND-Zen pre- and post-purification data, we obtain a preliminary lower limit on the 0\nu\beta\beta decay half-life of T_{1/2}^{0\nu} > 2.6 x 10^{25} yr at 90% C.L. The search sensitivity will be enhanced with additional low background data after the purification. Prospects for further improvements with future KamLAND-Zen upgrades are also presented.