Searching For Neutral Kaon Rare Decay KL ? p0?¯?.

Abstract

The KOTO E14 experiment is dedicated to searching for CP violating K0 L rare decay K0L → π0ν¯ν. Events having 2 photons from π0 decay with large transverse momentum and no other veto signals are selected. A signal box in the Pt - z plane is determined as signal region. Physics data taking of 100 hours during 2013 May accumulated 1.43×1018 protons on target . Single event sensitivity is (1.29±0.06stat±0.19sys)×10−8. Blind analysis is used to minimize cut bias. Expected number of background event is 0.36 ± 0.16 and after opening the box, 1 event is observed. The corresponding upper limit branching ratio is 5.03 × 10−8 at 90% confidence level.