Invited Seminar: Search for rare kaon decays at the J-PARC KOTO experiment

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Overview

The KOTO experiment at the J-PARC 30GeV Main Ring is dedicated to search for the rare decay, 𝐾_𝐿→𝜋0𝜈𝜈. This mode, which directly violate the CP symmetry, is highly suppressed in the Standard Model (SM) and its branching ratio can be predicted precisely. These features make this decay one of the best probes to search for new physics beyond the SM.

We had published the results of the analysis of the dataset taken in 2016-2018. In the analysis, the largest background source came from a small contamination of charged kaons in the neutral beam. In 2021, we installed a new counter in the beam to suppress the charged kaon background.

In this seminar, I will report the results of the 2016-2018 analysis, the status of recent data taking and the future prospect.