133 research outputs found

    Inclusive jet cross section in pˉp{\bar p p} collisions at s=1.8\sqrt{s}=1.8 TeV

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    The inclusive jet differential cross section has been measured for jet transverse energies, ETE_T, from 15 to 440 GeV, in the pseudorapidity region 0.1â‰€âˆŁÎ·âˆŁâ‰€\leq | \eta| \leq 0.7. The results are based on 19.5 pb−1^{-1} of data collected by the CDF collaboration at the Fermilab Tevatron collider. The data are compared with QCD predictions for various sets of parton distribution functions. The cross section for jets with ET>200E_T>200 GeV is significantly higher than current predictions based on O(αs3\alpha_s^3) perturbative QCD calculations. Various possible explanations for the high-ETE_T excess are discussed.Comment: 8 pages with 2 eps uu-encoded figures Submitted to Physical Review Letter

    Search for charged Higgs decays of the top quark using hadronic tau decays

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    We present the result of a search for charged Higgs decays of the top quark, produced in ppˉp\bar{p} collisions at √s=\surd s = 1.8 TeV. When the charged Higgs is heavy and decays to a tau lepton, which subsequently decays hadronically, the resulting events have a unique signature: large missing transverse energy and the low-charged-multiplicity tau. Data collected in the period 1992-1993 at the Collider Detector at Fermilab, corresponding to 18.7±\pm0.7~pb−1^{-1}, exclude new regions of combined top quark and charged Higgs mass, in extensions to the standard model with two Higgs doublets.Comment: uuencoded, gzipped tar file of LaTeX and 6 Postscript figures; 11 pp; submitted to Phys. Rev.

    Measurement of Dijet Angular Distributions at CDF

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    We have used 106 pb^-1 of data collected in proton-antiproton collisions at sqrt(s)=1.8 TeV by the Collider Detector at Fermilab to measure jet angular distributions in events with two jets in the final state. The angular distributions agree with next to leading order (NLO) predictions of Quantum Chromodynamics (QCD) in all dijet invariant mass regions. The data exclude at 95% confidence level (CL) a model of quark substructure in which only up and down quarks are composite and the contact interaction scale is Lambda_ud(+) < 1.6 TeV or Lambda_ud(-) < 1.4 TeV. For a model in which all quarks are composite the excluded regions are Lambda(+) < 1.8 TeV and Lambda(-) < 1. 6 TeV.Comment: 16 pages, 2 figures, 2 tables, LaTex, using epsf.sty. Submitted to Physical Review Letters on September 17, 1996. Postscript file of full paper available at http://www-cdf.fnal.gov/physics/pub96/cdf3773_dijet_angle_prl.p

    Search for New Particles Decaying to Dijets at CDF

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    We have used 106 pb^-1 of data collected with the Collider Detector at Fermilab to search for new particles decaying to dijets. We exclude at the 95% confidence level models containing the following new particles: axigluons and flavor universal colorons with mass between 200 and 980 GeV/c, excited quarks with mass between 80 and 570 GeV/c^2 and between 580 and 760 GeV/c^2, color octet technirhos with mass between 260 and 480 GeV/c^2, W' bosons with mass between 300 and 420 GeV/c^2, and E_6 diquarks with mass between 290 and 420 GeV/c^2.Comment: 18 pages, 4 figures, 1 table. Submitted to Physical Review D Rapid Communications. Postscript file of paper is also available at http://www-cdf.fnal.gov/physics/pub97/cdf3276_dijet_search_prd_rc.p

    Search for New Particles Decaying to Dijets in p-pbar Collisions at sqrt(s)=1.8 TeV

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    We have used 19 pb**-1 of data collected with the Collider Detector at Fermilab to search for new particles decaying to dijets. We exclude at 95% confidence level models containing the following new particles: axigluons with mass between 200 and 870 GeV, excited quarks with mass between 80 and 570 GeV, and color octet technirhos with mass between 320 and 480 GeV.Comment: Submitted to Physical Review Letters in December 199

    The Charge Asymmetry in W-Boson Decays Produced in p-pbar Collisions at sqrt(s) = 1.8 TeV

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    The charge asymmetry has been measured using 19,039 W19,039~W decays recorded by the CDF detector during the 1992-93 run of the Tevatron Collider. The asymmetry is sensitive to the ratio of dd and uu quark distributions to x<0.01x<0.01 at Q2≈MW2Q^2 \approx M_W^2, where nonperturbative effects are minimal. It is found that of the two current sets of parton distributions, those of Martin, Roberts and Stirling (MRS) are favored over the sets most recently produced by the CTEQ collaboration. The WW asymmetry data provide a stronger constraints on d/ud/u ratio than the recent measurements of F2ÎŒn/F2ÎŒpF_2^{\mu n}/F_2^{\mu p} which are limited by uncertainties originating from deutron corrections.Comment: to be published in PR

    Measurement of σ⋅B(W→eÎœ)\sigma \cdot B (W \to e \nu) and σ⋅B(Z0→e+e−)\sigma \cdot B(Z^0 \to e^+e^-) in ppˉp {\bar p} collisions at s=1.8\sqrt{s}=1.8 TeV

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    We present a measurement of σ⋅B(W→eÎœ)\sigma \cdot B(W \to e \nu) and σ⋅B(Z0→e+e−)\sigma \cdot B(Z^0 \to e^+e^-) in proton - antiproton collisions at s=1.8\sqrt{s} =1.8 TeV using a significantly improved understanding of the integrated luminosity. The data represent an integrated luminosity of 19.7 pb−1^{-1} from the 1992-1993 run with the Collider Detector at Fermilab (CDF). We find σ⋅B(W→eÎœ)=2.49±0.12\sigma \cdot B(W \to e \nu) = 2.49 \pm 0.12~nb and σ⋅B(Z0→e+e−)=0.231±0.012\sigma \cdot B(Z^0 \to e^+e^-) = 0.231 \pm 0.012~nb.Comment: Uses Latex, Article 12 point, figure appended as uuencoded file The full PostScript available via WWW at http://www-cdf.fnal.gov/physics/pub95/cdf3312_sigma_1a_prl_v3.p

    Measurement of correlated Ό−overlineb\mu - {overline b} jet cross sections in ppˉp {\bar p} collisions at s=1.8\sqrt{s}=1.8 TeV

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    We report on measurements of differential Ό−bˉ\mu - {\bar b} cross sections, where the muon is from a semi-leptonic bb decay and the bˉ{\bar b} is identified using precision track reconstruction in jets. The semi-differential correlated cross sections, dσ\sigma/d\Et^{{\bar b}}, dσ\sigma/d\pt^{{\bar b}}, and dσ\sigma/dÎŽÏ•(Ό−bˉ)\delta\phi(\mu - {\bar b}) for \pt^{\mu}>~9 GeV/c, âˆŁÎ·ÎŒâˆŁ|\eta^{\mu}|~10 GeV, ∣ηbˉ∣<|\eta^{{\bar b}}|<~1.5, are presented and compared to next-to-leading order QCD calculations.Comment: Uses Latex, Article 12 point, figures appended as uuencoded file The full PostScript available via WWW at http://www-cdf.fnal.gov/physics/pub95/cdf3164_mu_bbar_prd_final.p

    Further Properties of High-Mass Multijet Events at the Fermilab Proton-Antiproton Collider

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    The properties of high-mass multijet events produced at the Fermilab proton-antiproton collider are compared with leading order QCD matrix element predictions, QCD parton shower Monte Carlo predictions, and the predictions from a model in which events are distributed uniformly over the available multibody phase-space. Multijet distributions corresponding to (4N-4) variables that span the N-body parameter space are found to be well described by the QCD calculations for inclusive three-jet, four-jet, and five-jet events. The agreement between data, QCD Matrix Element calculations, and QCD parton shower Monte Carlo predictions suggests that 2 -> 2 scattering plus gluon radiation provides a good first approximation to the full LO QCD matrix element for events with three, four, or even five jets in the final state.Comment: 49 pages with 19 figures. Submitted to Phys. Rev. D. PostScript with full resolution figures also available at http://www-cdf.fnal.gov/physics/pub96/cdf3480_multijet_prd_draft3.p
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