Search for the decay KL0→3γK_L^0 \rightarrow 3\gamma

We performed a search for the decay $K_L^0 \rightarrow 3\gamma$ with the E391a detector at KEK. In the data accumulated in 2005, no event was observed in the signal region. Based on the assumption of $K_L^0 \rightarrow 3\gamma$ proceeding via parity-violation, we obtained the single event sensitivity to be $(3.23\pm0.14)\times10^{-8}$, and set an upper limit on the branching ratio to be $7.4\times10^{-8}$ at the 90% confidence level. This is a factor of 3.2 improvement compared to the previous results. The results of $K_L^0 \rightarrow 3\gamma$ proceeding via parity-conservation were also presented in this paper

Experimental study of the decay KL0→π0ννˉK_L^0\to\pi^0\nu\bar{\nu}

The first dedicated search for the rare neutral-kaon decay $K_L^0\to\pi^0\nu\bar{\nu}$ has been carried out in the E391a experiment at the KEK 12-GeV proton synchrotron. The final upper limit of 2.6 $\times 10^{-8}$ at the 90% confidence level was set on the branching ratio for the decay.Comment: 23 pages, 27 figures, accepted for publication as a regular article in Physical Review

The Physics of the B Factories

This work is on the Physics of the B Factories. Part A of this book contains a brief description of the SLAC and KEK B Factories as well as their detectors, BaBar and Belle, and data taking related issues. Part B discusses tools and methods used by the experiments in order to obtain results. The results themselves can be found in Part C

A new search for the KL→π0νν‾K_{L} \to \pi^0 \nu \overline{\nu} and KL→π0X0K_{L} \to \pi^{0} X^{0} decays

We searched for the CP-violating rare decay of the neutral kaon, KL→π0νν¯, in data from the first 100 hours of physics running in 2013 of the J-PARC KOTO experiment. One candidate event was observed while 0.34±0.16 background events were expected. We set an upper limit of 5.1×10−8 for the branching fraction at the 90% confidence level (C.L.). An upper limit of 3.7×10−8 at the 90% C.L. for the KL→π0X0 decay was also set for the first time, where X0 is an invisible particle with a mass of 135 MeV/c2.We searched for the $CP$-violating rare decay of neutral kaon, $K_{L} \to \pi^0 \nu \overline{\nu}$, in data from the first 100 hours of physics running in 2013 of the J-PARC KOTO experiment. One candidate event was observed while $0.34\pm0.16$ background events were expected. We set an upper limit of $5.1\times10^{-8}$ for the branching fraction at the 90\% confidence level (C.L.). An upper limit of $3.7\times10^{-8}$ at the 90\% C.L. for the $K_{L} \to \pi^{0} X^{0}$decay was also set for the first time, where $X^{0}$ is an invisible particle with a mass of 135 MeV/$c^{2}$