Related papers: First Observation and Study of the $K^\pm \to \pi^…
Recent measurements by the NA48 at CERN of selected $K_L$ decays are presented. These are the branching ratios and form factors for channels $K_L\to \pi^{\pm}\pi^0\e^{\mp}\nu_e$ (final result), $K_L\to\pi^{\pm}e^{\mp}\nu_e$ and $K_L\to…
The NA48/2 and NA62-$R_K$ experiments at the CERN SPS collected large samples of charged kaon decays in flight in 2003--07. The data analysis is still on-going (with over 20 publications produced so far); the recent results from these…
A sample of $4.687\times 10^6$ fully reconstructed $K^\pm\to\pi^\pm\pi^0_D$, $\pi^0_D\to\gamma e^+e^-$ decay candidates in the kinematic range $m_{ee}>10~{\rm MeV}/c^2$ with a negligible background contamination collected by the NA48/2…
The NA48/2 result, based on the data collected during the 2003 run, on direct CP violation in $K^{\pm}\to\pi^{\pm}\pi^0\pi^0$ decay is presented. The main goal of the experiment is to reach a sensitivity at level of $10^{-4}$ in the…
The NA48/2 Collaboration at CERN has accumulated unprecedented statistics of rare kaon decays in the Ke4 modes: Ke4(+-) ($K^\pm \to \pi^+ \pi^- e^\pm \nu$) and Ke4(00) ($K^\pm \to \pi^0 \pi^0 e^\pm \nu$) with nearly one percent background…
The first observations of the rare decays KS->pi0e+e- and KS->pi0mu+mu- have been made by the NA48/1 collaboration at the CERN SPS accelerator. From high intensity KS data collected during the 2002 run, clean signals of 7 KS->pi0e+e- events…
The NA48/2 and $\text{NA62}\text{-}{\text{R}_\text{K}}$ experiments at the CERN SPS collected a large sample of charged kaon decays in flight. $\text{NA62}\text{-}{\text{R}_\text{K}}$ was running in 2007-08 with a highly efficient minimum…
A search for the decay $K_S\to\pi^0\gamma\gamma$ has been made using the NA48 detector at the CERN SPS. Using data collected in 1999 during a 40-hour run with a high-intensity $K_S$ beam, an upper limit for the branching ratio…
New results on radiative K+- decays from the NA48/2 experiment are presented. In the channel K+- -> pi+- pi0 gamma more than 1 million decays were reconstructed, leading to the first measurement of the interference between direct photon…
NA62 is a fixed target kaon experiment at the CERN SPS which aims at measuring the branching ratio of the $K^+\to\pi^+\nu\bar{\nu}$ decay with 10% precision. This ultra-rare kaon decay is theoretically extremely clean and an ideal place to…
We report on the measurement of the direct emission (DE) and interference (INT) terms of the K\pm -> \pi\pm\pi^0 g decay by the NA48/2 experiment at the CERN SPS. From the data collected during 2003 and 2004 about 600k such decay candidates…
The first search for ultra-rare $K^+$ decays into the $\pi^+e^+e^-e^+e^-$ final state is reported, using a dataset collected by the NA62 experiment at CERN in 2017-2018. An upper limit of $1.4\times 10^{-8}$ at 90% CL is obtained for the…
Using the NA48 detector at the CERN SPS, 31 KS->pi0 gamma gamma candidates with an estimated background of 13.7 +- 3.2 events have been observed. This first observation leads to a branching ratio of BR(KS->pi0 gamma gamma) = (4.9 +-…
The NA48/2 experiment at the CERN SPS collected in 2003 and 2004 large samples of the decays K+- -> pi+ pi- e+- nu (Ke4+-), K+- -> pi0 pi0 e+- nu (Ke400) and K+- -> pi0 pi0 pi+-. From the Ke4+- form factors and from the cusp in the M00^2…
Recent results from the NA48/2 and NA62 kaon decay-in-flight experiments at CERN are presented. A precision measurement of the helicity-suppressed ratio RK of the K+- to e+- nu and K+- to mu+- nu decay rates has been performed using the…
The NA48/2 experiment at CERN collected a large sample of charged kaon decays into final states with multiple charged particles in 2003--2004. A new upper limit on the rate of the lepton number violating decay $K^{\pm} \to \pi^{\mp}…
A sample of 65210 $\mathrm{K^{\pm}} \rightarrow \pi^{0} \pi^{0} \mathrm{e^{\pm}} \nu$ ($\mathrm{K}_{\mathrm{e}4}^{00}$) decay candidates with $1\%$ background contamination has been collected in 2003$-$2004 by the NA48/2 collaboration at…
The CERN NA62 experiment uses a novel "kaon decay-in-flight" technique to observe $K^+ \to \pi^+ \nu \overline{\nu}$. The preliminary result based on the analysis of the full 2016 dataset will be presented. In agreement with the Standard…
Recent results from the experiments NA48, NA48/1 and NA48/2 are presented, including: direct CP-violation and Dalitz plot slopes measurements for K+- --> 3 pi decays; pi pi scattering effects in K+- --> pi+- pi0 pi0 and Ke4 decays, as well…
The decay rate of $\klpgg$ has been measured with the NA48 detector at the CERN SPS. A total of 2558 $\klpgg$ candidates have been observed with a residual background of 3.2%. The branching ratio is determined to be $(1.36 \pm0.03_{(stat)}…