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arXiv 2012.07571hep-ex
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KOTO实验中$K_L \!\to\! π^0 ν\overlineν$衰变的研究

Study of the $K_L \!\to\! π^0 ν\overlineν$ Decay at the J-PARC KOTO Experiment

KOTO Collaboration, J. K. Ahn, B. Beckford, M. Campbell, S. H. Chen, J. Comfort, K. Dona, M. S. Farrington, K. Hanai, N. Hara, H. Haraguchi, Y. B. Hsiung, M. Hu… 展开作者

KOTO Collaboration, J. K. Ahn, B. Beckford, M. Campbell, S. H. Chen, J. Comfort, K. Dona, M. S. Farrington, K. Hanai, N. Hara, H. Haraguchi, Y. B. Hsiung, M. Hutcheson, T. Inagaki, M. Isoe, I. Kamiji, T. Kato, E. J. Kim, J. L. Kim, H. M. Kim, T. K. Komatsubara, K. Kotera, S. K. Lee, J. W. Lee, G. Y. Lim, Q. S. Lin, C. Lin, Y. Luo, T. Mari, T. Masuda, T. Matsumura, D. Mcfarland, N. McNeal, K. Miyazaki, R. Murayama, K. Nakagiri, H. Nanjo, H. Nishimiya, Y. Noichi, T. Nomura, T. Nunes, M. Ohsugi, H. Okuno, J. C. Redeker, J. Sanchez, M. Sasaki, N. Sasao, T. Sato, K. Sato, Y. Sato, N. Shimizu, T. Shimogawa, T. Shinkawa, S. Shinohara, K. Shiomi, R. Shiraishi, S. Su, Y. Sugiyama, S. Suzuki, Y. Tajima, M. Taylor, M. Tecchio, M. Togawa, T. Toyoda, Y. -C. Tung, Q. H. Vuong, Y. W. Wah, H. Watanabe, T. Yamanaka, H. Y. Yoshida, L. Zaidenberg

备注：
6 pages, 5 figures; published version, no change in the results. Fig. 2 and Fig. 4 were revised. In Fig. 5, the plot of the $P_{t}$ versus ${Z_{\mathrm{vtx}}}$ of the beam-halo $K_L\!\to\!2γ$ background events was added as Fig. 5 (b)
发表信息：
Phys. Rev. Lett. 126, 121801 (2021)
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摘要：

利用2016年、2017年和2018年在J-PARC KOTO实验中采集的数据集研究了稀有衰变$K_L \!\to\! π^0 ν\overlineν$。在单事件灵敏度为$( 7.20 \pm 0.05_{\rm stat} \pm 0.66_{\rm syst} ) \times 10^{-10}$的情况下，在信号区域中观察到三个候选事件。在揭示它们之后，研究了来自$K^{\pm}$和分散的$K_L$衰变的污染物，估计背景事件的总数为$1.22 \pm 0.26$。我们的结论是，观察到的事件的数量在统计上与背景预期一致。对于该数据集，我们在90%置信水平下对$K_L \!\to\! π^0 ν\overlineν$的分支分数设置了$4.9 \times 10^{-9}$的上限。

英文摘要：

The rare decay $K_L \!\to\! π^0 ν\overlineν$ was studied with the dataset taken at the J-PARC KOTO experiment in 2016, 2017, and 2018. With a single event sensitivity of $( 7.20 \pm 0.05_{\rm stat} \pm 0.66_{\rm syst} ) \times 10^{-10}$, three candidate events were observed in the signal region. After unveiling them, contaminations from $K^{\pm}$ and scattered $K_L$ decays were studied, and the total number of background events was estimated to be $1.22 \pm 0.26$. We conclude that the number of observed events is statistically consistent with the background expectation. For this dataset, we set an upper limit of $4.9 \times 10^{-9}$ on the branching fraction of $K_L \!\to\! π^0 ν\overlineν$ at the 90% confidence level.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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