1,296 research outputs found

    Measurement of the Inclusive Semi-electronic D0D^0 Branching Fraction

    Get PDF
    Using the angular correlation between the π+\pi^+ emitted in a D+D0π+D^{*+} \rightarrow D^0 \pi^+ decay and the e+e^+ emitted in the subsequent D0Xe+νD^0 \rightarrow Xe^+\nu decay, we have measured the branching fraction for the inclusive semi-electronic decay of the D0D^0 meson to be: {\cal B}(D^0 \rightarrow X e^+ \nu) = [6.64 \pm 0.18 (stat.) \pm 0.29 (syst.)] \%. The result is based on 1.7 fb1^{-1} of e+ee^+e^- collisions recorded by the CLEO II detector located at the Cornell Electron Storage Ring (CESR). Combining the analysis presented in this paper with previous CLEO results we find, \frac{{\cal B} (D^0 \rightarrow X e^+ \nu)} {{\cal B} (D^0 \rightarrow K^- \pi^+)} = 1.684 \pm 0.056 (stat.) \pm 0.093(syst.) and \frac{{\cal B}(D\rightarrow K^-e^+\nu)} {{\cal B}(D\rightarrow Xe^+\nu)} = 0.581 \pm 0.023 (stat.) \pm 0.028(syst.). The difference between the inclusive rate and the sum of the measured exclusive branching fractions (measured at CLEO and other experiments) is (3.3±7.2)%(3.3 \pm 7.2) \% of the inclusive rate.Comment: Latex file, 33pages, 4 figures Submitted to PR

    Determination of the Michel Parameters and the tau Neutrino Helicity in tau Decay

    Get PDF
    Using the CLEO II detector at the e+ee^+e^- storage ring CESR, we have determined the Michel parameters ρ\rho, ξ\xi, and δ\delta in τlννˉ\tau^\mp \to l^\mp\nu\bar{\nu} decay as well as the tau neutrino helicity parameter hντh_{\nu_\tau} in τππ0ν\tau^\mp \to \pi^\mp\pi^0\nu decay. From a data sample of 3.02×1063.02\times 10^6 tau pairs produced at s=10.6GeV\sqrt{s}=10.6 GeV, using events of the topology e+eτ+τ(l±ννˉ)(ππ0ν)e^+e^- \to \tau^+\tau^- \to (l^\pm\nu\bar{\nu}) (\pi^\mp\pi^0\nu) and e+eτ+τ(π±π0νˉ)(ππ0ν)e^+e^- \to \tau^+\tau^- \to (\pi^\pm\pi^0\bar{\nu}) (\pi^\mp\pi^0\nu), and the determined sign of hντh_{\nu_\tau}, the combined result of the three samples is: ρ=0.747±0.010±0.006\rho = 0.747\pm 0.010\pm 0.006, ξ=1.007±0.040±0.015\xi = 1.007\pm 0.040\pm 0.015, ξδ=0.745±0.026±0.009\xi\delta = 0.745\pm 0.026\pm 0.009, and hντ=0.995±0.010±0.003h_{\nu_\tau} = -0.995\pm 0.010\pm 0.003. The results are in agreement with the Standard Model V-A interaction.Comment: 18 page postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

    Search for the Decay τ4pi3π+(π0)ντ\tau^{-}\to 4pi^{-}3\pi^{+}(\pi^{0})\nu_{\tau}

    Full text link
    We have searched for the decay of the tau lepton into seven charged particles and zero or one pi0. The data used in the search were collected with the CLEO II detector at the Cornell Electron Storage Ring (CESR) and correspond to an integrated luminosity of 4.61 fb^(-1). No evidence for a signal is found. Assuming all the charged particles are pions, we set an upper limit on the branching fraction, B(tau- -> 4pi- 3pi+ (pi0) nu_tau) < 2.4 x 10^(-6) at the 90% confidence level. This limit represents a significant improvement over the previous limit.Comment: 9 page postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

    Limit on the Two-Photon Production of the Glueball Candidate fJ(2220)f_{J}(2220) at CLEO

    Full text link
    We use the CLEO detector at the Cornell electron-positron storage ring, CESR, to search for the two-photon production of the glueball candidate f_J(2220) in its decay to K_s K_s. We present a restrictive upper limit on the product of the two-photon partial width and the K_s K_s branching fraction. We use this limit to calculate a lower limit on the stickiness, which is a measure of the two-gluon coupling relative to the two-photon coupling. This limit on stickiness indicates that the f_J(2220) has substantial glueball content.Comment: 9 page postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

    Measurement of Br(D0Kπ+)Br(D^{0}\to K^{-}\pi^{+}) using Partila Reconstruction of BˉD+Xνˉ\bar{B}\to D^{*+}X\ell^{-}\bar{\nu}

    Full text link
    We present a measurement of the absolute branching fraction for D0>Kpi+D^0 -> K^- pi^+ using the reconstruction of the decay chain Bbar>D+XlnubarBbar -> D^{*+} X l^- nubar , D+>D0pi+D^{*+} -> D^0 pi^+ where only the lepton and the low-momentum pion from the D+D^{*+} are detected. With data collected by the CLEO II detector at the Cornell Electron Storage Ring, we have determined Br(D0>Kpi+)=[3.81+0.15(stat.)+0.16(syst.)]Br(D^0 -> K^- pi^+)= [3.81 +- 0.15(stat.) +- 0.16(syst.)]%.Comment: 10 page postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

    Investigation of Semileptonic BB Meson Decay to P-Wave Charm Mesons

    Full text link
    We have studied semileptonic BB meson decays with a P-wave charm meson in the final state using 3.29 x 10^6 B\bar{B} events collected by the CLEO~II detector at the Cornell Electron-positron Storage Ring. We find a value for the exclusive semileptonic product branching fraction: Br(B^- -> D_1^0 l^- \bar{\nu}) x Br(D_1^0 -> D^{*+}\pi^-) = (0.373 \pm 0.085 \pm 0.052 \pm 0.024)% and an upper limit for Br(B^- -> D_2^{*0} l^- \bar{\nu}) x Br(D_2^{*0} -> D^{*+}\pi^-) < 0.16%$ (90% C.L.). These results indicate that at least 20% of the total B^- semileptonic rate is unaccounted for by the observed exclusive decays, B^- -> D^0 l^- \bar{\nu}, B^- -> D^{*0} l^- \bar{\nu}, B^- -> D_1^0 l^- \bar{\nu}, and B^- -> D_2^{*0} l^- \bar{\nu}.Comment: 10 page postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

    Flavor-Specific Inclusive B Decays to Charm

    Get PDF
    We have measured the branching fractions for B -> D_bar X, B -> D X, and B -> D_bar X \ell^+ \nu, where ``B'' is an average over B^0 and B^+, ``D'' is a sum over D^0 and D^+, and``D_bar'' is a sum over D^0_bar and D^-. From these results and some previously measured branching fractions, we obtain Br(b -> c c_bar s) = (21.9 ±\pm 3.7)%, Br(b -> s g) K^- \pi^+) = (3.69 ±\pm 0.20)%. Implications for the ``B semileptonic decay problem'' (measured branching fraction being below theoretical expectations) are discussed. The increase in the value of Br(b -> c c_bar s) due to B>DXB -> D X eliminates 40% of the discrepancy.Comment: 12 page postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

    Measurement of the Branching Ratios for the Decays of Ds+ηπ+,ηπ+,ηρ+D_{s}^{+}\to \eta\pi^{+}, \eta^{'}\pi^{+}, \eta\rho^{+}, and etaρ+eta^{'}\rho^{+}

    Full text link
    Using a data sample with integrated luminosity of about 3.9 fb^{-1} collected in e+ e- annihilation with the CLEO-II detector at the Cornell Electron Storage Ring, we have measured the branching ratios for the decay modes Ds -> (eta, eta') pi and Ds -> (eta, eta') rho relative to Ds -> phi pi. These decay modes are among the most common hadronic decays of the Ds's and can be related by factorization to the semileptonic decays Ds -> (eta,eta') l nu. The results obtained are compared with previous CLEO results and with the branching ratios measured for the related semileptonic decays. We also report results on the Cabibbo-suppressed decays of the D+ to the same final states.Comment: 18 page postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

    Measurement of the BˉDνˉ\bar{B}\to D\ell\bar{\nu} Partila Width and Form Factor Parameters

    Full text link
    We have studied the decay BˉDνˉ\bar{B} \to D\ell\bar{\nu}, where =eorμ\ell=e or \mu. From a fit to the differential decay rate dΓ/dwd\Gamma/dw we measure the rate normalization FD(1)Vcb{\cal F}_D(1)|V_{cb}| and form factor slope ρ^D2\hat{\rho}^2_D, and, using measured values of τB\tau_B, find Γ(BˉDνˉ)=(12.0±0.9±2.1)ns1\Gamma(\bar{B} \to D\ell\bar{\nu}) = (12.0 \pm 0.9 \pm 2.1) ns^{-1}. The resulting branching fractions are B(Bˉ0D+νˉ)=(1.87±0.15±0.32){\cal B}(\bar{B}^0 \to D^+\ell^-\bar{\nu})=(1.87 \pm 0.15 \pm 0.32)% and B(BD0νˉ)=(1.94±0.15±0.34){\cal B}(B^- \to D^0\ell^-\bar{\nu})=(1.94 \pm 0.15 \pm 0.34)%. The form factor parameters are in agreement with those measured in BˉDνˉ\bar{B} \to D^*\ell\bar{\nu} decays, as predicted by heavy quark effective theory.Comment: 11 pages, postscript file also available through http://w4.lns.cornell.edu/public/CLN
    corecore