KamLAND-Zen 800 Status and Prospect with the Artificial Intelligence Powered Analysis

Abstract

Abstract The discovery of neutrinoless double beta decay (0υββ) would shed light on the persistent puzzle surrounding the origin of neutrino mass and help explain the matter-dominated universe. KamLAND-Zen is one of the leading experiments searching for 0υββ. The first phase of the experiment, called KamLAND-Zen 400, set a world-leading limit on 0υββ lifetime. After the conclusion of KamLAND-Zen 400, a brand new mini-balloon with a larger volume and cleaner surface were instrumented to contain 745 kg of 136Xe. Since Jan. 2019, KamLAND-Zen 800 has started data-taking and aims to improve on the previous 0υββ result. A detailed study of the backgrounds in this new data will be presented along with a state-of-the-art approach for classifying backgrounds using a new algorithm called KamNet. The rejection power of KamNet does not rely on coincidence tagging and scales with hardware updates. With the help of KamNet, the 0υββ sensitivity of KamLAND-Zen 800 is significantly enhanced to a new summit.