Related papers: Kaon-Scatter Introduced Backgrounds in the KOTO Ex…
The KOTO experiment was designed to observe and study the K$^{0}_{L} \rightarrow$ $\pi^{0}\nu\bar{\nu}$ decay at J-PARC. The Standard Model (SM) prediction for the process is (3.0 $\pm$ 0.3) x 10$^{-11}$ with small uncertainties. This…
The KOTO experiment at the J-PARC research facility in Tokai, Japan aims to observe and measure the rare decay of the neutral kaon, $K_L^0 \rightarrow \pi^0 \nu \bar{\nu}$. This decay has a Standard Model (SM) predicted branching ratio (BR)…
The KOTO II experiment is proposed to measure the branching ratio of the decay $K_L\to\pi^0\nu\bar{\nu}$ at J-PARC. With a beamline to extract long-lived neutral kaons at 5 degrees from a production target, the single event sensitivity of…
We have performed a search for the K$^{0}_{L} \rightarrow \pi^{0}\nu\bar{\nu}$ decay with the KOTO detector at J-PARC. The KOTO detector was designed to observe the decay and measure its branching ratio (BR). Focusing on this golden decay…
The rare kaon decay $K_L\to\pi^0\nu\bar{\nu}$ is extremely sensitive to new physics, because the contribution to this decay in the Standard Model (SM) is highly suppressed and known very accurately; the branching ratio is $3\times 10^{-11}$…
The KOTO ($K^0$ at Tokai) experiment aims to observe the CP-violating rare decay $K_L \rightarrow \pi^0 \nu \bar{\nu}$ by using a long-lived neutral-kaon beam produced by the 30 GeV proton beam at the Japan Proton Accelerator Research…
We performed a search for the $K_L \to \pi^{0} \nu \bar{\nu}$ decay using the data taken in 2021 at the J-PARC KOTO experiment. With newly installed counters and new analysis method, the expected background was suppressed to…
The KOTO experiment aims to discover the rare decay $K^{0}_{L}\rightarrow \pi^{0} \nu \bar{\nu}$ at J-PARC. This mode breaks the CP symmetry directly and is highly suppressed in the Standard Model. Thus the mode is sensitive to new physics,…
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…
The experimental status of the $K \to \pi \nu \bar{\nu}$ search is presented. The $K \to \pi \nu \bar{\nu}$ decay is sensitive to New Physics because it is theoretically pristine and highly suppressed. The $K_L^0 \to \pi^0 \nu \bar{\nu}$…
Recently, the KOTO experiment reported their new preliminary result of searching for the decay $K_L\to\pi^0\nu\bar{\nu}$. Three candidate events were observed in the signal region, which exceed significantly the expectation based on the…
While the main goal of the J-PARC KOTO experiment is to measure the rare decay $K_L \to \pi^0 \nu \bar \nu$, the unique setup of KOTO raises the possibility to search for physics beyond the Standard Model, in an attempt to probe parts of…
We performed searches for $K_L\rightarrow \pi^0\pi^0X$ where $X$ may be an axion-like particle which promptly decays to two photons, and the first search for $K_L \rightarrow \pi^0\pi^0\gamma\gamma$ at the KOTO experiment using data taken…
The rare decay $K_L \!\to\! \pi^0 \nu \overline{\nu}$ was studied with the dataset taken at the J-PARC KOTO experiment in 2016, 2017, and 2018. With a single event sensitivity of $( 7.20 \pm 0.05_{\rm stat} \pm 0.66_{\rm syst} ) \times…
Recent measurements of kaon decays provide new information about CKM unitarity, lepton universality, and discrete symmetries. KLOE-2, the proposed extension of the kaon physics program at Frascati, will extend the world data set on kaon…
The latest search for the rare kaon decay $K^+\to\pi^+\nu\bar\nu$ by the NA62 experiment has produced evidence for it with a branching fraction consistent with the prediction of the standard model. The new result implies that in this decay,…
Kaon experiments are now focusing on searching for new physics beyond the standard model. For example, CERN NA62, J-PARC KOTO and J-PARC TREK-E36 experiments are starting up to study K->pi nu nu-bar decay modes, a lepton flavor violation,…
The two kaon factories, KOTO and NA62, are at the cutting edge of the intensity frontier, with an unprecedented numbers of long lived and charged Kaons, ~ 10^{13}, being measured and analyzed. These experiments have currently a unique…
The KOTO experiment recently reported four candidate events in the signal region of $K_L\to \pi^0 \nu\bar\nu$ search, where the standard model only expects $0.10\pm 0.02$ events. If confirmed, this requires physics beyond the standard model…
The KOTO experiment has recently performed a search for neutral Kaons decaying into neutral pions and a pair of neutrinos. Three events were observed in the KOTO signal region, with an expected background of about 0.05. Since no clear…