Related papers: New results from the NA48/2 experiment at CERN SPS…
The distribution of the $K^\pm\to\pi^\pm\pi^+\pi^-$ decays in the Dalitz plot has been measured by the NA48/2 experiment at the CERN SPS with a sample of $4.71\times 10^8$ fully reconstructed events. With the standard Particle Data Group…
We have observed 1 event consistent with the signature expected of the rare decay of a positive kaon to a positive pion and a neutrino anti-neutrino pair. In the examined momentum region of 211 to 230 MeV/c in the center of mass of the kaon…
Searches for lepton number violating $K^+\to\pi^-e^+e^+$ and $K^+\to\pi^-\pi^0e^+e^+$ decays have been performed using the complete dataset collected by the NA62 experiment at CERN in 2016-2018. Upper limits of $5.3\times 10^{-11}$ and…
The NA48 experiment at CERN aims at making a precision study of direct CP violation in the neutral kaons, by measuring $Re(\epsilon'/\epsilon)$ with an accuracy better than 0.02%. To achieve this goal, the experiment requires a neutral…
High-intensity proton beams impinging on a fixed target or beam dump allow to probe new physics via the production of new weakly-coupled particles in hadron decays. The CERN SPS provides opportunities to do so with the running NA62…
The branching ratio (BR) for the decay K^+ \to \pi^+\nu\bar{\nu} is a sensitive probe for new physics. The NA62 experiment at the CERN SPS will measure this BR to within about 10%. To reject the background from dominant kaon decays with…
The ratio R_K=Gamma(Ke2)/Gamma(Kmu2) provides a very powerful probe for the weak interactions structure. This ratio of decay rates is calculated with very high precision within the Standard Model but the corrections due to the presence of…
We report here a measurement of form factors of $K^{\pm}_{\mu 3}$ decay by the NA48/2 experiment at CERN. Using a sample of 3.4$\times10^6$ events we provide preliminary form factor values according to various parametrizations. The slope of…
The main aim of the NA62 experiment at CERN is to study the rare $K^+ \rightarrow \pi^+ \nu \bar{\nu}$ decay and measure its Branching Ratio (BR) with $10%$ precision. Due to its theoretical precision, this decay is an excellent probe to…
The NA62 experiment at CERN SPS is aimed to measure the branching ratio of the ultra-rare decay $K^+\rightarrow\pi^+ \nu \bar{\nu}$ with 10\% accuracy. The experiment operates with a 75 GeV/c high intensity (750 MHz) secondary beam. A new…
Additional evidence for the rare kaon decay K+ to pi+ neutrino-antineutrino has been found in a new data set with comparable sensitivity to the previously reported result. One new event was observed in the pion momentum region examined,…
A search for heavy neutral lepton production in $K^+$ decays using a data sample collected with a minimum bias trigger by the NA62 experiment at CERN in 2015 is reported. Upper limits at the $10^{-7}$ to $10^{-6}$ level are established on…
A high statistics data sample of the decays of $K^+$ mesons to three charged particles was accumulated by the OKA experiment in 2012 and 2013. This allowed to select a clean sample of about 450 events with…
The NA62 experiment is a fixed-target experiment at CERN SPS. The main goal of the experiment is to measure the branching ratio of the ultra-rare kaon decay $K^{+}\to\pi^{+}\nu\bar\nu$. The NA62 detector allows also to study other rare kaon…
In this paper I will describe the search for rare kaon decay processes $K^+\to \pi^+ \nu \bar\nu$ and $K^0_L \to \pi^0 \nu \bar\nu$. The small decay rate for these processes is considered a key prediction of the standard model. We searched…
Improved branching ratios were measured for the $K_L \to 3 \pi^0 $ decay in a neutral beam at the CERN SPS with the NA31 detector: $\Gamma (K_L \to 3 \pi^0) / \Gamma (K_L \to \pi^+ \pi^- \pi^0) = 1.611 \pm 0.037$ and $\Gamma (K_L \to 3…
A high precision search for direct CP-violation in K+- --> 3 pi decays was performed by the NA48/2 experiment at CERN SPS. The asymmetry in the Dalitz plot linear slopes A_g = (g^+ - g^-)/(g^+ + g^-) is measured to be A^c_g = (-1.3 +-…
We present a global analysis of leptonic and semileptonic kaon decays data, including all recent results by BNL-E865, KLOE, KTeV, ISTRA+, and NA48. Experimental results are critically reviewed and combined, taking into account theoretical…
The NA48 experiment at CERN has performed a measurement of direct CP violation in the neutral kaon system, based on data collected in 1997 and 1998. The preliminary result for the parameter $\Re(\epsilon^{\prime}/\epsilon)$ is $(14.0 \pm…
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,…