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We present new measurements of the six largest branching fractions of the K L using data collected in 1997 by the KTeVexperiment (E832) at Fermilab. 0:010† 10 ÿ3 , where statistical and systematic errors have been summed in quadrature. We also determine the CP violation parameter j ‡ÿ j to be …2:228 0:010† 10 ÿ3. Several of these results are not in good(More)
The KTeV E799 experiment has conducted a search for the rare decays, K(L)→π(0)π(0)μ(+)μ(-) and K(L)→π(0)π(0)X(0)→π(0)π(0)μ(+)μ(-), where the X(0) is a possible new neutral boson that was reported by the HyperCP experiment with a mass of (214.3 ± 0.5) MeV/c(2). We find no evidence for either decay. We obtain upper limits of(More)
The KTeV/E799 experiment at Fermilab has searched for the rare kaon decay K(L)-->pi(0)e(+)e(-). This mode is expected to have a significant CP violating component. The measurement of its branching ratio could support the standard model or could indicate the existence of new physics. This Letter reports new results from the 1999-2000 data set. One event is(More)
The polarization of Ξ 0 and Ξ 0 hyperons produced by 800 GeV/c protons on a BeO target at a fixed targeting angle of 4.8 mrad is measured by the KTeV experiment at Fermilab. Our result of 9.7% for Ξ 0 polarization shows no significant energy dependence when compared to a result obtained at 400 GeV/c production energy and at twice our targeting angle. The(More)
This Letter is the first report of the K{L}-->pi{+/-}e{-/+}nue{+}e{-} decay. Based on 19 208+/-144 events, we determine the branching fraction, B(K{L}-->pi{+/-}e{-/+}nue{+}e{-}M_{e{+}e{-}}>5 MeV/c{2},E{e{+}e{-}}{*}>30 MeV)=(1.285+/-0.041)x10{-5}, and Gamma(K{e3ee}M{e{+}e{-}}>5 MeV/c{2})/Gamma(K{e3})=[4.57+/-0.04(stat)+/-0.14(syst)]x10{-5}. This ratio agrees(More)
We present a determination of the Cabibbo-Kobayashi-Maskawa parameter |V(us)| based on new measurements of the six largest K(L) branching fractions and semileptonic form factors by the KTeV (E832) experiment at Fermilab. We find |V(us)|=0.2252+/-0.0008(KTeV)+/-0.0021(ext), where the errors are from KTeV measurements and from external sources. We also use(More)
The Fermilab KTeV experiment has searched for lepton-flavor-violating decays of the K(L) meson in three decay modes. We observe no events in the signal region for any of the modes studied, and we set the following upper limits for their branching ratios at the 90% C.L.: BR(K(L) --> pi(0) micro(+/-) e(-/+)) <7.6 x 10(-11); BR(K(L) --> pi(0)pi(0) micro(+/-)(More)
Using the complete KTeV data set of 5,241 candidate K(L)--> pi(+) pi(-) e(+) e(-) decays (including an estimated background of 204 +/- 14 events), we have measured the coupling g(CR)= 0.163 +/- 0.0149(stat) +/- 0.023(syst) of the CP conserving charge radius process and from it determined a K(0) charge radius of <r(2)(K(0))> = [-0.077 +/- 0.007(stat) +/-(More)