135 research outputs found

    MEASUREMENT OF THE RATIO SIGMA-B(P(P)OVER-BAR-]W-]E-NU)/SIGMA-B(P(P)OVER-BAR-]Z(O)-]EE) IN P(P)OVER-BAR COLLISIONS AT ROOT-S=1800 GEV

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    We present an analysis of data from p ()overbarpcollisionsatacenterofmassenergyofroots=1800GeV.AmeasurementismadeoftheratioR=sigmaB(p() over bar p collisions at a center-of-mass energy of root s = 1800 GeV. A measurement is made of the ratio R = sigma B(p () over bar p --> W --> ev)/sigma B(p ($) over bar p --> Z(0) --> ee). The data represent 19.6 pb(-1) collected by the Collider Detector at Fermilab during the 1992-1993 collider run of the Fermilab Tevatron. We find R = 10.90 +/- 0.32(stat)+/-0.29(syst), and from this value we extract a measurement of the W --> ev branching ratio Gamma(W --> ev)/Gamma(W) = 0.1094+/-0.0033(stat)+/-0.0031(syst). From this branching ratio we set a limit on the top quark mass of mt > 62 GeV/c(2) at the 95% confidence level. In contrast with direct searches for the top quark, this limit makes no assumptions about the allowed decay modes of the top quark. In addition, we use a calculation of the leptonic width Gamma(W --> ev) to obtain a value for the W total decay width:Gamma(W) = 2.064+/-0.060(stat)+/-0.059(syst) GeV

    Measurement of the Isolated Prompt Photon Cross-section In (p)bar-p Collisions At Root-s = 1.8 Tev

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    We present a measurement of the cross section for production of isolated prompt photons in ppBAR collisions at square-root s = 1.8 TeV. The cross section, measured as a function of transverse momentum (P(T)), agrees qualitatively with QCD calculations but has a steeper slope at low P(T)

    Measurement of double parton scattering in (p)over-bar-p collisions at root s=1.8 TeV

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    A strong signal for double parton scattering (DP) is observed in a 16 pb(-1) sample of (p) over bar p(-1) sample of (p) over bar p --> gamma + 3 jets + X data from the CDF experiment at the Fermilab Tevatron. The process-independent DP parameter, sigma(eff), is obtained without reference to theoretical calculations by comparing observed DP events to events with hard scatterings at separate (p) over bar p collisions. The result, sigma(eff) = (14.5 +/- 1.7(-2.3)(+1.7)) mb. represents a significant improvement over previous measurements. For the first time, the Feynman x dependence of the sigma(eff) parameter is investigated, and no dependence is seen

    Evidence For Color Coherence In P(p)over-bar Collisions At Root-s=1.8 Tev

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    Color coherence effects in p ($) over bar p collisions are observed and studied with CDF, the Collider Detector at the Fermilab Tevatron collider. We demonstrate these effects by measuring spatial correlations between soft and leading jets in multijet events. Variables sensitive to interference are identified by comparing the data to the predictions of various shower Monte Carlo programs that are substantially different with respect to the implementation of coherence

    UPSILON-PRODUCTION IN P(P)OVER-BAR COLLISIONS AT ROOT-S=1.8 TEV

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    We report on measurements of the Upsilon(1S), Upsilon(2S), and Upsilon(3S) differential, (d(2) sigma/dP(t)dy)(y=0), and integrated cross sections in p (p) over bar collisions at root s = 1.8 TeV using a sample of 16.6 +/- 0.6 pb(-1) collected by the Collider Detector at Fermilab. The three resonances were reconstructed through the decay Upsilon --> mu(+)mu(-). Comparison is made to a leading order QCD prediction

    Search for third generation leptoquarks in (p)over-bar-p collisions at root s=1.8 TeV

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    We present the results of a search for third generation leptoquark (LQ) pairs in 110 +/- 8 pb(-1) of (p) over bar p collisions at root s = 1.8 TeV recorded by the Collider Detector at Fermilab. We assume third generation leptoquarks decay to a tau lepton and a b quark with branching ratio beta. We observe one candidate event, consistent with standard model background expectations. We place upper limits on sigma((p) over bar p --> LQ().beta(2) as a function of the leptoquark mass M(LQ). We exclude at 95% confidence level scalar leptoquarks with M(LQ) < 99 GeV/c(2), gauge vector leptoquarks with M(LQ) < 225 GeV/c(2), and nongauge vector leptoquarks with M(LQ) < 170 GeV/c(2) for beta = 1

    Properties of jets in W boson events from 1.8 TeV (p)over-bar-p collisions

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    We present a study of events with W bosons and hadronic jets produced in (p) over bar p collisions at a center of mass energy of 1.8 TeV. The data consist of 51400 W+/--->e(+/-)v decay candidates from 108 pb(-1) of integrated luminosity collected using the CDF detector at the Fermilab Tevatron Collider. Cross sections and jet production properties have been measured for W+ greater than or equal to 1 to greater than or equal to 4 jet events. The data are compared to predictions of leading-order QCD matrix element calculations with added gluon radiation and simulated parton fragmentation

    Search For 2nd-generation Leptoquarks In P(p)over-bar Collisions At Root-s=1.8 Tev

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    We present the results of a search for second generation leptoquarks S-2 using 19.3 pb(-1) of data collected at the Collider Detector at Fermilab (CDF) in p (p) over bar collisions at root s = 1.8 TeV during the 1992-93 collider run. We have searched for S-2 (S) over bar(2) pairs assuming that each leptoquark decays to a muon + quark with a branching ratio beta. We find two candidate events, consistent with an expected background of 1.11 +/- 0.48. We obtain upper limits on sigma(pp --> S-2 (S) over bar(2))beta(2) as a function of M(S2). Using a Monte Carlo prediction for S-2 (S) over bar(2) pair production, we exclude M(S2) < 131 GeV/c(2) for beta = 1 and M(S2) < 95 GeV/c(2) for beta = 0.5 at 95% C.L

    Search for chargino-neutralino production in p(p)over-bar collisions at root s=1.8 TeV

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    We have searched for chargino-neutralino production ((1)+/-(0)(2)) in 1.8 TeV collisions, followed by their leptonic decays (0)(1)l(+/-)nu and (0)(2)-->(0)(1)l(+)l(-). These trilepton events are expected within a framework of the minimal supersymmetric standard model (MSSM). In a 19.1 pg(-1) data sample collected with a Collider Detector at Fermilab, no trilepton events were observed. Upper limits on sigma(p (p) over bar-->(+/-)(1)(0)(2)). BR((+/-)(1)(0)(2)-->3l+X) were obtained for various MSSM parameter space regions, yielding new 95% confidence level lower limits for the neutralino ((0)(2)) mass which extend as high as 49 GeV/c(2)
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