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【摘要】

KOTO is the dedicated experiment to study the K0L → π0νν decay. This decay is regarded as the golden channel to search for New Physics because its branching ratio is predicted to be 3.0 × 10−11 with only 2% uncertainty. By using the data collected from 2016 through 2018, KOTO had reached the single event sensitivity of O(10−9) and found three signal candidate events. However, an extensive investigation after opening the box revealed two additional background sources: scattered K0L and K+ in the neutral beam. In order to suppress them, KOTO has upgraded the detector and developed analysis tools since 2020. With these new features, KOTO has maintained the small number of background events at the similar sensitivity to the previous result. In this seminar, the latest result will be presented and the projection toward the future will also be given.