117 research outputs found

    Reconstruction of B-0->J/psi K-S(0) and measurement of ratios of branching ratios involving B->J/psi K* and B+->J/psi K+

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    We report on the reconstruction of the decay mode B-0 --> J/psi K-S(0) using 19.3 pb(-1) of data collected by the Collider Detector at Fermilab in collisions at root s = 1.8 TeV. A signal of 41.8 +/- 6.9 events, with a signal-to-background ratio of 9:1, is observed. Three additional decay modes B+ --> J/psi K+, B-0 --> J/psi K*(892)(0), and B+ --> J/psi K*(892)(+) are reconstructed. We measure three ratios of branching ratios, each one relative to the B+ --> J/psi K+ mode. We also report the ratio of decay rates, Gamma(B --> J/psi K*)/Gamma(B --> J/psi K), for the vector-vector relative to the vector-pseudoscalar modes, to be 1.32 +/- 0.23(stat) +/- 0.16(syst)

    Neutral pion production from deuterium at the LEGS facility

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    Neutral pion photoproduction from a liquid deuterium target was measured in the energy region near 300 MeV at the LEGS facility of Brookhaven National Laboratory. The inclusive cross sections from deuterium are in agreement with measurments from Mainz, yet the exclusive cross sections and spin asymmetries for neutral pion production in coincidence with a detected nucleon are much smaller than expected from a quasi-free approximation. This may indicate that substantial final state interactions play a significant role, which will complicate the extraction of the desired amplitudes that would be measured if a free neutron target could be used

    MEASUREMENT OF THE POLARIZATION IN THE DECAYS B-D-]J/PSI-K-(ASTERISK-0) AND BS-]J/PSI-PHI

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    This Letter reports on measurements of the longitudinal polarization fractions in the decays B-d --> J/psi K*(0) and B-s --> J/psi phi using data collected with the Collider Detector at Fermilab. B-d mesons are reconstructed through the decay chain B-d --> J/psi K*(0), J/psi --> mu(+)mu(-), K*(0) --> K(+)phi(-). A sample of 65 +/- 10 B-d events is used to obtain a longitudinal polarization fraction of T-L/Gamma = 0.65 +/- 0.10(stat) +/- 0.04(syst). B-s mesons are reconstructed through the decay chain B-s --> J/psi phi, J/psi --> mu(+)mu(-), phi --> K+K-. A sample of 19 +/- 5 B-s events is used to obtain the result Gamma(L)/Gamma = 0.56 +/- 0.21(stat)-(+0.02)(0.04)(syst)

    MEASUREMENT OF THE B-MESON B-QUARK CROSS-SECTIONS AT ROOT-S=1.8 TEV USING THE EXCLUSIVE DECAY B(0)-]J/PSI-K-ASTERISK(892)0

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    This paper reports the measurement of the B meson and b quark cross sections through the decay chain B0 --> J/psi K* (892)0, J/psi --> mu+ mu-, K* (892)0 --> K+ pi-, using 4.3 pb-1 of data collected at the Collider Detector at Fermilab in pBARp collisions at square-root s = 1.8 TeV. We obtain sigma(B) = 1.5 +/- 0.7(stat)+/-0.6(syst) mub for B0 mesons with transverse momentum P(T) > 9.0 GeV/c and rapidity \y\ 11.5 GeV/c and rapidity \y\ < 1.0. The b quark cross section is compared to next-to-leading order QCD calculations and previous measurements

    Search for flavor-changing neutral current B meson decays in p(p)over-bar collisions at root s=1.8 TeV

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    We report on a search for the flavor-changing neutral current decays B d,s 0 → μ+μ-, B+ → μ+μ-K+ and B0 → μ+μ-K*0 using data from pp̄ collisions at √s = 1.8 TeV, collected with the Collider Detector at Fermilab during the 1992-1993 running period. We find no indication of such decays, and we set the following 90% confidence level upper limits on branching ratios: B(B0 → μ+μ-) < 1.6 × 10-6, B(BS 0 → μ+μ-) < 8.4 × 10-6, B(B+ → μ+μ-K+) < 1.0 × 10-5, and B(B0 → μ+μ-K*0) < 2.5 × 10-5

    Measurement of the mass of the B-s(0) meson

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    We measure the mass of the B-s(0) meson by reconstructing the decay chain B-s(0)-->J/psi phi, J/psi-->mu(+)mu(-), and phi-->K+K-. The data are obtained from 19.3 pb(-1) of integrated luminosity of collisions at root s=1.8 TeV using the Collider Detector at Fermilab. A sample of 80 000 inclusive J/psi-->mu(+)mu(-) events is used to study systematic biases in track reconstruction and to calibrate the momentum scale. We reconstruct the kinematically similar decays B+-->J/mu K+ and B-0-->J/psi K*(0) to study the mass measurement technique used for the B-s(0) meson. Based on the observation of 32 +/- 6 candidates, the mass of the B-s(0) meson is measured to be 5369.9 +/- 2.3 +/- 1.3 MeV/c(2) and the mass difference between B-s(0) and the average mass of B+ and B-0 is determined to be 89.7 +/- 2.7 +/- 1.2 MeV/c(2)

    Measurement of the lifetime of the Bs0 meson using the exclusive decay mode Bs0 → J/ψ φ

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    The lifetime of the B0s meson is measured using the exclusive decay mode B0s→J/ψφ, where J/ψ→μ+μ− and φ→K+K−. The data sample consists of 110pb−1 of pp ̄ collisions at √s=1.8TeV, collected by the CDF detector at the Fermilab Tevatron collider during 1992–1995. We find 58±12 signal events, and the B0s meson lifetime is determined to be τB0s=1.34+0.23−0.19(stat)±0.05(syst) ps. This result is consistent with previous measurements of the B0s, B+, and B0d meson lifetimes and with theoretical predictions

    OBSERVATION OF THE DECAY B(S)0-]J-PSI-PHI IN (P)OVER-BAR-P COLLISIONS AT ROOT-S = 1.8 TEV

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    This Letter reports the observation and mass measurement of fully reconstructed B(s)0 mesons through the decay chain B(s)0 --> J/psiphi, J/psi --> mu+mu-, phi --> K+K- using data obtained at the Collider Detector at Fermilab in ppBAR collisions at square-root s = 1.8 TeV. A signal of 14.0 +/- 4.7 events is observed. Comparison of the B(s)0 signal with the kinematically similar decays B+ --> J/psiK+ and B0 --> J/psiK*(892)0 is presented. The mass of the B(s)0 meson is determined to be 5383.3 +/- 4.5 (stat) +/- 5.0 (syst) MeV/c2

    MEASUREMENT OF THE B-S MESON LIFETIME

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    The lifetime of the Bs meson is measured using the semileptonic decay Bs→Ds-+νX. The data sample consists of 19.3 pb-1 of pp̄ collisions at s=1.8 TeV collected by the Collider Detector at Fermilab during 1992-1993. There are 76±8 +Ds- signal events where the Ds is identified via the decay Ds-→φπ-, φ→K+K-. Using these events, the Bs meson lifetime is determined to be τs=1.42-0.23+0.27(stat)±0.11(syst) ps. A measurement of the Bs lifetime in a low statistics sample of exclusive Bs→J/ψ φ decays is also presented in this paper. © 1995 The American Physical Society

    MEASUREMENT OF THE B-MESON DIFFERENTIAL CROSS-SECTION D-SIGMA/DP(T) IN P(P)OVER-BAR COLLISIONS AT ROOT-S=1.8 TEV

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    This paper presents the first direct measurement of the B meson differential cross section dσ/dpT in pp̄ collisions at s=1.8 TeV using a sample of 19.3±0.7 pb-1 accumulated by the Collider Detector at Fermilab. The cross section is measured in the central rapidity region |y|6.0 GeV /c by fully reconstructing the B meson decays B+→J/ψK+ and B0→J/ψK*0892, where J/ψ→μ+μ- and K*0→K+π-. A comparison is made to the theoretical QCD prediction calculated at next-to-leading order. © 1995 The American Physical Society
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