S. Hayashida

Results from KamLAND-Zen

KamLAND-Zen reports on a preliminary search for neutrinoless double-beta decay with 136Xe based on 114.8 live-days after the purification of the xenon loaded liquid scintillator. In this data, the problematic 110mAg 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 0νββ decay half-life of T1/20ν>2.6×1025 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.

Search for the proton decay mode p → ν ¯ K+ with KamLAND SEARCH for the PROTON DECAY MODE ⋯ K. ASAKURA et al

We present a search for the proton decay mode

Search for the proton decay mode p -> ¯νK+ with KamLAND

p\ensuremath{\rightarrow}\overline{\ensuremath{\nu}}{K}^{+}

Search for the proton decay modep→ν¯K+with KamLAND

based on an exposure of 8.97 kton-years in the KamLAND experiment. The liquid scintillator detector is sensitive to successive signals from

Search for the proton decay mode with KamLAND

p\ensuremath{\rightarrow}\overline{\ensuremath{\nu}}{K}^{+}

Search for the proton decay mode

with unique kinematics, which allow us to achieve a detection efficiency of 44%, higher than previous searches in water Cherenkov detectors. We find no evidence of proton decays for this mode. The expected background, which is dominated by atmospheric neutrinos, is

p \rightarrow \overline{\nu} K^{+}

0.9\ifmmode\pm\else\textpm\fi{}0.2

with KamLAND

events. The nonbackground-subtracted limit on the partial proton lifetime is

Search for Majorana Neutrinos Near the Inverted Mass Hierarchy Region with KamLAND-Zen

\ensuremath{\tau}/B(p\ensuremath{\rightarrow}\overline{\ensuremath{\nu}}{K}^{+})g5.4\ifmmode\times\else\texttimes\fi{}{10}^{32}\text{ }\text{ }\mathrm{years}

Publisher's Note: Search for Majorana Neutrinos Near the Inverted Mass Hierarchy Region with KamLAND-Zen [Phys. Rev. Lett. 117, 082503 (2016)].

at 90% C.L.