e-Article
Search for Majorana Neutrinos with the Complete KamLAND-Zen Dataset
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Working Paper
Author
Abe, S.; Araki, T.; Chiba, K.; Eda, T.; Eizuka, M.; Funahashi, Y.; Furuto, A.; Gando, A.; Gando, Y.; Goto, S.; Hachiya, T.; Hata, K.; Ichimura, K.; Ieki, S.; Ikeda, H.; Inoue, K.; Ishidoshiro, K.; Kamei, Y.; Kawada, N.; Kishimoto, Y.; Koga, M.; Marthe, A.; Matsumoto, Y.; Mitsui, T.; Miyake, H.; Morita, D.; Nakajima, R.; Nakamura, K.; Nakamura, R.; Nakane, J.; Ono, T.; Ozaki, H.; Saito, K.; Sakai, T.; Shimizu, I.; Shirai, J.; Shiraishi, K.; Suzuki, A.; Tachibana, K.; Tamae, K.; Watanabe, H.; Watanabe, K.; Yoshida, S.; Umehara, S.; Fushimi, K.; Kotera, K.; Urano, Y.; Berger, B. E.; Fujikawa, B. K.; Learned, J. G.; Maricic, J.; Fu, Z.; Ghosh, S.; Smolsky, J.; Winslow, L. A.; Efremenko, Y.; Karwowski, H. J.; Markoff, D. M.; Tornow, W.; Dell'Oro, S.; O'Donnell, T.; Detwiler, J. A.; Enomoto, S.; Decowski, M. P.; Weerman, K. M.; Grant, C.; Penek, O.; Song, H.; Li, A.; Axani, S. N.; Garcia, M.; Sarfraz, M.
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Abstract
We present a search for neutrinoless double-beta ($0\nu\beta\beta$) decay of $^{136}$Xe using the full KamLAND-Zen 800 dataset with 745 kg of enriched xenon, corresponding to an exposure of $2.097$ ton yr of $^{136}$Xe. This updated search benefits from a more than twofold increase in exposure, recovery of photo-sensor gain, and reduced background from muon-induced spallation of xenon. Combining with the search in the previous KamLAND-Zen phase, we obtain a lower limit for the $0\nu\beta\beta$ decay half-life of $T_{1/2}^{0\nu} > 3.8 \times 10^{26}$ yr at 90% C.L., a factor of 1.7 improvement over the previous limit. The corresponding upper limits on the effective Majorana neutrino mass are in the range 28-122 meV using phenomenological nuclear matrix element calculations.
Comment: arXiv admin note: text overlap with arXiv:2203.02139
Comment: arXiv admin note: text overlap with arXiv:2203.02139