A new search for the KL → π0ν ν and KL → π 0X0 decays

J. K. Ahn, K. Y. Baek, S. Banno, B. Beckford, B. Brubaker, T. Cai, M. Campbell, C. Carruth, S. H. Chen, S. Chu, J. Comfort, Y. T. Duh, T. Furukawa, H. Haraguchi, T. Hineno, Y. B. Hsiung, M. Hutcheson, T. Inagaki, M. Isoe, E. IwaiT. Kamibayashi, I. Kamiji, N. Kawasaki, E. J. Kim, Y. J. Kim, J. W. Ko, T. K. Komatsubara, A. S. Kurilin, G. H. Lee, H. S. Lee, J. W. Lee, S. K. Lee, G. Y. Lim, C. Lin, J. Ma, Y. Maeda, T. Masuda, T. Matsumura, D. McFarland, J. Micallef, K. Miyazaki, K. Morgan, R. Murayama, D. Naito, K. Nakagiri, Y. Nakajima, Y. Nakaya, H. Nanjo, T. Nomura, T. Nomura, Y. Odani, R. Ogata, H. Okuno, T. Ota, Y. D. Ri, M. Sasaki, N. Sasao, K. Sato, T. Sato, S. Seki, T. Shimogawa, T. Shinkawa, S. Shinohara, K. Shiomi, J. S. Son, J. Stevens, S. Su, Y. Sugiyama, S. Suzuki, Y. Tajima, G. Takahashi, Y. Takashima, M. Tecchio, I. Teo, M. Togawa, T. Toyoda, Y. C. Tung, T. Usuki, Y. W. Wah, H. Watanabe, N. Whallon, J. K. Woo, J. Xu, M. Yamaga, S. Yamamoto, T. Yamanaka, H. Yamauchi, Y. Yanagida, H. Yokota, H. Y. Yoshida, H. Yoshimoto

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34 Citations (Scopus)


We searched for the CP-violating rare decay of the neutral kaon, KL → π0ν ν, in data from the first 100 hours of physics running in 2013 of the J-PARC KOTO experiment. One candidate event was observed while 0.34 ± 0.16 background events were expected.We set an upper limit of 5.1 × 10-8 for the branching fraction at the 90% confidence level (C.L.). An upper limit of 3.7 × 10-8 at the 90% C.L. for the KL → π0X0 decay was also set for the first time, where X0 is an invisible particle with a mass of 135 MeV/c2.

Original languageEnglish
Article number021C01
JournalProgress of Theoretical and Experimental Physics
Issue number2
Publication statusPublished - 2017 Feb 1

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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