The KOTO experiment at J-PARC recently showed an unexpected data on KL to pi0 nu nu search. This channel is significantly suppressed in the standard model, and have not been measured yet. Besides, this channel is sensitive to CP violation of new physics. If the data is confirmed as signals, it strongly implies physics beyond the standard model. In this talk, I will introduce several new physics interpretations of the data. We have studied several new physics explanations in the context of a generalized new physics Grossman-Nir bound coming from the K+ to pi+ nu nu decay, which is bounded by data from the E949 and the NA62 experiments.

Reference:
arXiv:1909.11111, Phys. Rev. Lett. 124, 071801 (2020)

Slides: Kitahara_KMI