相关论文: First observation of the KS->pi0 gamma gamma decay
The KS->gamma gamma decay rate has been measured with the NA48 detector using a high intensity short neutral beam from the CERN SPS. The measured branching ratio BR(KS->gamma gamma)=(2.78+-0.06(stat)+-0.04(syst))x10-6, obtained from…
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…
In data taken with the NA48 experiment at the CERN SPS in 1999, 730 candidates of the weak radiative hyperon decay Xi0 -> Lambda gamma have been found with an estimated background of 58+-8 events. From these events the Xi0 -> Lambda gamma…
From the 2002 data taking with a neutral kaon beam extracted from the CERN-SPS, the NA48/1 experiment observed 97 $\Xi^{0}\rightarrow \Sigma^{+} \mu^{-} \bar{\nu}_{\mu}$ candidates with a background contamination of $30.8 \pm 4.2$ events.…
Using the full data set of the NA48/2 experiment, the decay K+- -> pi+- e+ e- gamma is observed for the first time, selecting 120 candidates with 7.3 +- 1.7 estimated background events. With K+- -> pi+- pi0D as normalisation channel, the…
The NA48/2 experiment at CERN collected two data samples with minimum bias trigger conditions in 2003 and 2004. A measurement of the rate and dynamic properties of the rare decay $K^\pm\to\pi^\pm\gamma\gamma$ from these data sets based on…
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…
A search for the decay K_S -> pi^0mu^+mu^- has been made by the NA48/1 Collaboration at the CERN SPS accelerator. The data were collected during 2002 with a high-intensity K_S beam. Six events were found with a background expectation of…
A search for the decay Ks->pi0e+e- has been made by the NA48/1 experiment at the CERN SPS accelerator. Using data collected during 89 days in 2002 with a high-intensity Ks beam, 7 events were found with a background of 0.15 events. The…
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)}…
The NA48/2 experiment at CERN reports the first observation of the $K^\pm \to \pi^\pm \pi^0 e^+ e^-$ decay from an exposure of $1.7 \times 10^{11}$ charged kaon decays recorded in $2003-2004$. A sample of 4919 candidates with 4.9%…
Preliminary results on KL->pi e nu(gamma) decays collected by the NA48 detector at the CERN SPS are reported. Using a sample of 6.8 X 10^6 reconstructed events BR(Ke3) = 0.4010+-0.0028+-0.0035 was obtained. From the branching ratio the…
The $K_L\to\pi^{\pm}\pi^0e^{\mp}\nu_e(\bar\nu_e)$ decay was investigated with the NA48 detector at CERN SPS using a beam of long-lived neutral kaons. The branching ratio $Br(K_L\to\pi^{\pm}\pi^0e^{\mp}\nu_e(\bar\nu_e))=(5.21\pm…
The first observation of the decay K^+ --> pi^+ gamma gamma is reported. A total of 31 events was observed with an estimated background of 5.1 +- 3.3 events in the pi+ momentum range from 100 MeV/c to 180 MeV/c. The corresponding partial…
We report on the first observation of the decay KL -> pi0 ee gamma by the KTeV E799 experiment at Fermilab. Based upon a sample of 48 events with an estimated background of 3.6 +/- 1.1 events, we measure the KL -> pi0 ee gamma branching…
A sample of 3984 candidates of the $K^+\to\pi^+\gamma\gamma$ decay, with an estimated background of $291\pm14$ events, was collected by the NA62 experiment at CERN during 2017-2018. In order to describe the observed di-photon mass spectrum,…
From 56 days of data taking in 2002, the NA48/1 experiment observed 6316 Xi0 --> Sigma+ e- nubar candidates (with the subsequent Sigma+ --> p pi0 decay) and 555 anti-Xi0 --> anti-Sigma+ e+ nu candidates with background contamination of…
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…
The NA48/2 experiment at the CERN SPS carried out data taking in 2003 and 2004. Analysis of the selected data samples of 7,146 $K^\pm\to\pi^\pm e^+e^-$ decay candidates with 0.6% background, 1,164 $K^\pm\to\pi^\pm\gamma\gamma$ candidates…
The decay rate of the neutral long-lived K meson into the e+ e- e+ e- final state has been measured with the NA48 detector at the CERN SPS. Using data collected in 1999, a total of 132 events has been observed with negligible background.…