Related papers: First Observation of the Rare Decay Mode K-long ->…
In a sample of 19 million produced B mesons, we have observed the decays B -> eta K* and improved our previous measurements of B -> eta'K. The branching fractions we measure for these decay modes are BR(B+ -> eta K*+) = (26.4 +9.6-8.2 +-…
The first observation of the $B_s^0 \to \overline{D}^0 K^+ K^-$ decay is reported, together with the most precise branching fraction measurement of the mode $B^0 \to \overline{D}^0 K^+ K^-$. The results are obtained from an analysis of $pp$…
Experiment E949 at Brookhaven National Laboratory studied the rare decay \$K^+\to\pi^+\nu\bar{\nu}$ and other processes with an exposure of $1.77\times 10^{12}$ $K^+$'s. The data were analyzed using a blind analysis technique yielding one…
The rare kaon decay program at BNL is summarized. A brief review of recent results is provided along with a discussion of prospects for the future of this program. The primary focus is the two golden modes: k+->pnn and kl->pnn. The first…
We have observed the rare decay K+ --> pi+ mu+ mu- and measured the branching ratio Gamma(K+ --> pi+ mu+ mu-)/Gamma(K+ --> all) = (5.0 +/- 0.4 (stat.) +/- 0.7 (sys.) +/- 0.6 (theor.)) x 10^{-8}. We compare this result with predictions from…
Using about 23M $B \bar B$ events collected in 1999-2000 with the BABAR detector, we report the observation of several hundred $B \to D^{(*)}\bar D^{(*)}K$ decays with two completely reconstructed D mesons. The preliminary branching…
Recent results from the first phase of the E787 experiment and an update on the current status are presented. From the first phase the limit on the K+ -> pi+ nu nu (pnn) branching ratio is BR(pnn) < 2.4e-9 (90%CL). An observation of the…
We have performed a search for the angular-momentum forbidden decay K+ -> pi+ gamma with the E787 detector at BNL. No events were observed in the pi+ kinematic region around 227 MeV/c. An upper limit on the branching ratio for the decay is…
The KTeV/E799 experiment at Fermilab has searched for the rare kaon decay KL--> pi0ee. This mode is expected to have a significant CP violating component. The measurement of its branching ratio could support the Standard Model or could…
We report first observations of the decays B- to Ds(*)+ K- pi-, using 292 fb^-1 of data collected at Upsilon(4S) resonance energy by the BaBar detector at the PEP II e+ e- collider. The branching fractions are measured to be B(B- to Ds+ K-…
We study the decays B+ -> etac K+ and B0 -> etac K0, where the etac is reconstructed in the Ks K+ pi- and K+ K- pi0 decay modes. Results are based on a sample of 86 million BBbar pairs collected with the BaBar detector at the SLAC e+e- B…
We present the first model-independent measurement of the absolute branching fraction of the Lambda_c+ -> p K- pi+ decay using a data sample of 978 fb^-1 collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. The…
In a sample of 19 million produced B mesons we have observed decays B -> eta K*, and improved our previous measurements of B -> eta' K. The branching fractions we measure for these decay modes are B(B+ -> eta K*+) = (27.3 +9.6 -8.2 (stat)…
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 present measurements of the branching fraction and fraction of longitudinal polarization for the decay B+ -> K*0bar K*+ with a sample of 467 +/- 5 million BBbar pairs collected with the BaBar detector at the PEP-II asymmetric-energy e+e-…
We have observed the rare decay B0 => rho+ rho- in a sample of 89 million BB pairs recorded with the BABAR detector. The number of observed events is 88 +23-21 +-9, with a significance of 5.1 standard deviations with systematic…
We report a search for the rare decays B+ to D+ K0 and B+ to D+ K*0 in an event sample of approximately 465 million BBbar pairs collected with the BaBar detector at the PEP-II asymmetric-energy e+e- collider at SLAC. We find no significant…
In this report, we present the observation of the exclusive decays B0 -> EtaC K0 and B+ -> EtaC K+, and the measurement of the related branching fractions. Using a sample of 22.7x10^6 Upsilon(4S) -> BBbar decays collected with the BABAR…
The experimental program for the study of the rare kaon decays, K -> pnn, is summarized. A review of recent results is provided along with a discussion of prospects for the future of this program. The primary focus of the world-wide kaon…
We have searched for the rare decay of the eta meson $\eta \to e^{+}e^{-}$ using the CLEO II detector. The $\eta$'s were produced in $e^{+}e^{-}$ collisions with 10 GeV center-of-mass energy at the Cornell Electron Storage Ring (CESR). We…