Jeff Tseng

Abstract:

The kinematic properties of tt̄ events are studied in the W+ multijet channel using data collected with the CDF detector during the 1992-1995 runs at the Fermilab Tevatron collider corresponding to an integrated luminosity of 109 pb-1. Distributions of a variety of kinematic variables chosen to be sensitive to different aspects of tt̄ production are compared with those expected from Monte Carlo calculations. A sample of 34 events rich in tt̄ pairs is obtained by requiring at least one jet identified by the silicon vertex detector (SVX) as having a displaced vertex consistent with the decay of a b hadron. The data are found to be in good agreement with predictions of the leading order tt̄ matrix element with color coherent parton shower evolution. ©1999 The American Physical Society.

Abstract:

We present a detailed description of a search for anomalous production of missing ET (Slashed E signT), jets, leptons (e, μ, τ), b quarks, or additional photons in events containing two isolated, central (|η|<1.0) photons with ET>12 GeV. The results are consistent with standard model expectations, with the possible exception of one event that has, in addition to the two photons, a central electron, a high-ET electromagnetic cluster, and large Slashed E signT. We set limits using two specific SUSY scenarios for production of diphoton events with Slashed E signT. ©1999 The American Physical Society.

Abstract:

We present a measurement of Z0 boson and Drell-Yan production cross sections in p̄p collisions at √s =1.8TeV using a sample of 107 pb-1 accumulated by the Collider Detector at Fermilab. The Drell-Yan cross section is measured in the mass range of Mμμ>40GeV/c2. We compare the measurements with the predictions of quantum chromodynamics in both leading order and next-to-leading order, incorporating the recent parton distribution functions. The measurements are consistent with the standard model expectations. ©1999 The American Physical Society.

Abstract:

Bd0-B̄d0 oscillations are observed in "self-tagged" samples of partially reconstructed B mesons decaying into a lepton and a charmed meson collected in pp̄ collisions at √s=1.8 TeV. A flavor tagging technique is employed which relies upon the correlation between the flavor of B mesons and the charge of a nearby particle. We measure the flavor oscillation frequency to be Δmd=0.471-0.068+0.078±0.034 ps-1. The tagging method is also demonstrated in exclusive samples of Bu+→J/ψK+ and Bd0→J/ψK*0(892), where similar flavor-charge correlations are observed. The tagging characteristics of the various samples are compared with each other, and with Monte Carlo simulations.

Abstract:

The lifetime of the BS0 meson is measured using the semileptonic decay BS0→DS-l+νX. The data sample consists of about 110 pb-1 of pp̄ collisions at √s=1.8 TeV collected by the CDF detector at Fermilab. Four different DS- decay modes are reconstructed resulting in approximately 600 DS-l+ signal events. The BS0 meson lifetime is determined to be τ(BS0)=(1.36±0.09-0.05+0.06) ps, where the first and second uncertainties are statistical and systematic, respectively. The BS0 meson decay length distribution is examined for a lifetime difference ΔΓ/Γ between the two mass eigenstates of the BS0 meson. An upper limit of ΔΓ/Γ<0.83 is set at the 95% confidence level.