Search for the K_{L}→π^{0}νν[over ¯] Decay at the J-PARC KOTO Experiment.

• Tác giả: J K Ahn, M Farrington, M Gonzalez, N Grethen, K Hanai, N Hara, H Haraguchi, Y B Hsiung, T Inagaki, M Katayama, T Kato, Y Kawata, E J Kim, H M Kim, A Kitagawa, T K Komatsubara, K Kotera, S K Lee, X Li, G Y Lim, C Lin, Y Luo, T Mari, T Matsumura, I Morioka, H Nanjo, H Nishimiya, Y Noichi, T Nomura, K Ono, M Osugi, P Paschos, J Redeker, T Sato, Y Sato, T Shibata, N Shimizu, T Shinkawa, K Shiomi, R Shiraishi, S Suzuki, Y Tajima, N Taylor, Y C Tung, Y W Wah, H Watanabe, T Wu, T Yamanaka, H Y Yoshida
• Ngôn ngữ: eng
• Ký hiệu phân loại: 133.594 Types or schools of astrology originating in or associated with a
• Thông tin xuất bản: United States : Physical review letters , 2025
• Bộ sưu tập: NCBI
• ID: 707558

Tóm tắt

We performed a search for the K_{L}→π^{0}νν[over ¯] decay using the data taken in 2021 at the J-PARC KOTO experiment. With newly installed counters and new analysis method, the expected background was suppressed to 0.252±0.055_{stat} _{-0.067^{syst}}^{+0.052}. With a single event sensitivity of (9.33±0.06_{stat}±0.84_{syst})×10^{-10}, no events were observed in the signal region. An upper limit on the branching fraction for the decay was set to be 2.2×10^{-9} at the 90% confidence level (C.L.), which improved the previous upper limit from KOTO by a factor of 1.4. With the same data, a search for K_{L}→π^{0}X^{0} was also performed, where X^{0} is an invisible boson with a mass ranging from 1 to 260  MeV/c^{2}. For X^{0} with a mass of 135  MeV/c^{2}, an upper limit on the branching fraction of K_{L}→π^{0}X^{0} was set to be 1.6×10^{-9} at the 90% C.L.