相关论文: First Observation of the decay KL -> pi0 e e gamma

We report on a search for the decay \klpimumu carried out as a part of the KTeV experiment at Fermilab. This decay is expected to have a significant $CP$ violating contribution and a direct measurement will either support the CKM mechanism…

The KLOE experiment running at the phi-factory DAPHNE has collected ~ 450 pb^(-1) in the 2001--2002 data taking. We report preliminary results on light meson spectroscopy based on this data sample; particles are all produced through phi…

The radiative decay $B \to \phi K \gamma$ is observed for the first time. The branching fraction for the charged $B^- \to \phi K^- \gamma$ decay mode is measured to be ${\cal B}(B^- \to \phi K^- \gamma) = (3.4 \pm 0.9 \pm 0.4) \times…

We present a measurement of the ratio of the decay rates Gamma(KL -> pi+ pi-)/Gamma(KL -> pi e nu), denoted as Gamma(K2pi)/Gamma(Ke3). The analysis is based on data taken during a dedicated run in 1999 by the NA48 experiment at the CERN…

We have measured the ratio R=Gamma(K_L -> gamma gamma)/ \Gamma(K_L -> 3 pi^0) using the KLOE detector. From a sample of ~ 10^9 phi-mesons produced at DAFNE, the Frascati phi-factory, we select ~ 1.6 10^8 K_L-mesons tagged by observing K_S…

New measurements of K_L and K_S decays from the NA48 experiment are presented. From data taken in the year 2001, the value of the K_e3 charge asymmetry has been determined to delta_L(e) = (3.317 +- 0.070(stat) +- 0.072 (syst)) x 10^-3. From…

The aim of this work was to determine the KS -> 3pi0 decay branching ratio and a modulus of the eta000 parameter, defined as the ratio of amplitudes for KS -> 3 pi0 to KL -> 3pi0 decays, which characterizes the CP symmetry violation in this…

An integrated luminosity of 410 pb^(-1), corresponding to ~ 17 million of eta events, has been analyzed to measure the eta mass using the decay eta to gamma gamma. The measurement is insensitive to the calorimeter energy calibration and the…

We report on a measurement of the decay $K_L\rightarrow\mu^+\mu^-\gamma$ from Fermilab experiment E799. We observe $207$ candidate signal events with an estimated background of $10.5 \pm 4.0$ events and establish…

Preliminary results on the study of e+e- --> phi(1020) --> pi0 pi0 gamma, eta pi0 gamma processes from SND experiment at VEPP-2M collider in Novosibirsk are presented. Branching ratios of rare radiative phi --> pi0 pi0 gamma and phi --> pi0…

We report on results of an experimental search for the K_L -> pi^+ pi^- e^+ e^- decay mode. We found 13.5 +- 4.0 events and determined its branching ratio to be (4.4 +- 1.3(stat) +- 0.5(syst))*10^{-7}. The result agrees well with the…

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%…

We improve the calculations of the $\eta \to \pi^0 \gamma \gamma$ decay within the context of meson chiral lagrangians. We use a chiral unitary approach for the meson-meson interaction, thus generating the $a_0(980)$ resonance and fixing…

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…

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…

Using 9.0/fb of integrated luminosity in e+e- collisions near Upsilon(4S) mass collected with the CLEO II.V detector we report the first observation of the decay D0 -> K0S ETA PI0 We measure the ratio of branching fractions, BR(D0 -> K0S…

The branching ratio of the electromagnetic rare decays $\eta\to\pi^0\gamma\gamma$ and $\eta^\prime\to (\pi^0,\eta)\gamma\gamma$ are analysed in terms of scalar and vector meson exchange contributions using the frameworks of the Linear Sigma…

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…

The weak radiative decay Xi0 --> Lambda e+e- has been detected for the first time. We find 412 candidates in the signal region, with an estimated background of 15 +/- 5 events. We determine the branching fraction B(Xi0 --> Lambda e+e-) =…

We report measurements of radiative B decays with K eta gamma final states, using a data sample of 253 /fb recorded at the Upsilon(4S) resonance with the Belle detector at the KEKB e+e- storage ring. We observe B+ -> K+ eta gamma for the…