Now and future of the kaon program at J-PARC

CHIEH LIN^1*

¹Department of physics, National Changhua University of Education, Changhua City, Taiwan

* Presenter:CHIEH LIN, email:clin@gm.ncue.edu.tw

Rare kaon decays provide one of the most sensitive probes of New Physics. Among them, the K→πνν is the most appealing channel to search for because it is theoretically pristine and rare. KOTO at J-PARC is the dedicated experiment to search for this decay and has set the worldwide best limit on its branching ratio of 2.2 x 10^-9 (90% confidence level) using the data collected in 2021, which is two orders of magnitude larger than the Standard Model prediction. KOTO is expected to reach the sensitivity of O(10^-10) within 3-5 years. In order to precisely examine the Standard Model, we are now proposing the next-generation kaon experiment, KOTO-II, targeting the discovery of the K→πνν decay or New Physics. KOTO-II is expected to be the only kaon factory in the world and capable of exploring a wide range of physics topics, including the new CP-violating sources, light exotic particles, lepton-number-violating scenarios, etc. The KOTO-II experiment has the collaboration of 87 members from 11 countries and aims to start the operation from 2030, and the Taiwan group has taken a leadership role in the KOTO-II data-acquisition system. The overall status and prospects will be given in this presentation.

Keywords: kaon, rare decays, flavor physics, new physics