The Search for Neutrinoless Double Beta Decay in KamLAND-Zen 800

The discovery of neutrinoless double beta decay (0νββ) 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 0νββ. The first phase of the experiment, called KamLAND-Zen 400, set a world-leading limit on 0νββ lifetime. After the conclusion of KamLAND-Zen 400, a brand new mini-balloon with a larger volume and cleaner surface was instrumented to contain 745 kg of Xe136. Since Jan. 2019, KamLAND-Zen 800 has started data-taking and aims to improve on the previous 0νββ 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 impact of KamNet on KamLAND-Zen's 0νββ sensitivity will also be presented.