Speaker
Description
We report the status of the KOTO experiment at J-PARC to
search for the decay $K_L\to\pi^0\nu\overline{nu}$. The decay is sensitive to new
physics beyond the standard model because the standard model process is highly
suppressed in the decay. The branching ratio is $3\times 10^{-11}$ with small
theoretical uncertainty in the standard model. We set an upper limit of the
branching ratio at $3\times 10^{-9}$ with the data collected in 2015. We achieved
the single event sensitivity of $7.2\times 10^{-10}$ with 3 events observed for the
2016-2018 data analysis. The number of observed events is consistent to the
background estimations, and we introduced new measures against them, and
collected more data in 2019-2021. We will report the status, and the future
prospects including the KOTO step-2 aiming at the discovery of the decay.
