학술논문
A new search for the $K_{L} \to \pi^0 \nu \overline{\nu}$ and $K_{L} \to \pi^{0} X^{0}$ decays
Document Type
Working Paper
Author
Ahn, J. K.; Baek, K. Y.; Banno, S.; Beckford, B.; Brubaker, B.; Cai, T.; Campbell, M.; Carruth, C.; Chen, S. H.; Chu, S.; Comfort, J.; Duh, Y. T.; Furukawa, T.; Haraguchi, H.; Hineno, T.; Hsiung, Y. B.; Hutcheson, M.; Inagaki, T.; Isoe, M.; Iwai, E.; Kamibayashi, T.; Kamiji, I.; Kawasaki, N.; Kim, E. J.; Kim, Y. J.; Ko, J. W.; Komatsubara, T. K.; Kurilin, A. S.; Lee, G. H.; Lee, H. S.; Lee, J. W.; Lee, S. K.; Lim, G. Y.; Lin, C.; Ma, J.; Maeda, Y.; Masuda, T.; Matsumura, T.; Mcfarland, D.; Micallef, J.; Miyazaki, K.; Morgan, K.; Murayama, R.; Naito, D.; Nakagiri, K.; Nakajima, Y.; Nakaya, Y.; Nanjo, H.; Nomura, T.; Odani, Y.; Ogata, R.; Okuno, H.; Ota, T.; Ri, Y. D.; Sasaki, M.; Sasao, N.; Sato, K.; Sato, T.; Seki, S.; Shimogawa, T.; Shinkawa, T.; Shinohara, S.; Shiomi, K.; Son, J. S.; Stevens, J.; Su, S.; Sugiyama, Y.; Suzuki, S.; Tajima, Y.; Takahashi, G.; Takashima, Y.; Tecchio, M.; Teo, I.; Togawa, M.; Toyoda, T.; Tung, Y. C.; Usuki, T.; Wah, Y. W.; Watanabe, H.; Whallon, N.; Woo, J. K.; Xu, J.; Yamaga, M.; Yamamoto, S.; Yamanaka, T.; Yamauchi, H.; Yanagida, Y.; Yokota, H.; Yoshida, H. Y.; Yoshimoto, H.
Source
Prog. Theor. Exp. Phys. (2017) 021C01
Subject
Language
Abstract
We searched for the $CP$-violating rare decay of neutral kaon, $K_{L} \to \pi^0 \nu \overline{\nu}$, in data from the first 100 hours of physics running in 2013 of the J-PARC KOTO experiment. One candidate event was observed while $0.34\pm0.16$ background events were expected. We set an upper limit of $5.1\times10^{-8}$ for the branching fraction at the 90\% confidence level (C.L.). An upper limit of $3.7\times10^{-8}$ at the 90\% C.L. for the $K_{L} \to \pi^{0} X^{0}$decay was also set for the first time, where $X^{0}$ is an invisible particle with a mass of 135 MeV/$c^{2}$.
Comment: 11 pages, 5 figures, to be published in PTEP
Comment: 11 pages, 5 figures, to be published in PTEP