Status of KOTO Experiment at J-PARC

The KOTO experiment at the J-PARC laboratory seeks to obtain the first observation of the KL → π0v decay. The branching ratio is calculated in the Standard Model to be 2.4 × 10−11. This decay is a good probe to explore new physics beyond the Standard Model with its small theoretical uncertainty (~2%). In 2012 – 2013, KOTO performed commissioning runs with most of the detectors, and the first physics run started in May 2013. We accumulated 100 hours with the 24 kW beam power, and the analysis is on going. In this paper, the status of the KOTO experiment, including the data analysis and prospects, is reported.