4,667 research outputs found

    Report of the QCD Tools Working Group

    Get PDF
    We report on the activities of the ``QCD Tools for heavy flavors and new physics searches'' working group of the Run II Workshop on QCD and Weak Bosons. The contributions cover the topics of improved parton showering and comparisons of Monte Carlo programs and resummation calculations, recent developments in Pythia, the methodology of measuring backgrounds to new physics searches, variable flavor number schemes for heavy quark electro-production, the underlying event in hard scattering processes, and the Monte Carlo MCFM for NLO processes.Comment: LaTeX, 47 pages, 41 figures, 10 tables, uses run2col.sty, to appear in the Proceedings of the Workshop on "QCD and Weak Boson Physics in Run II", Fermilab, March - November 199

    Diversity of Arbuscular Mycorrhizal Fungi in the Rhizosphere of Solaris and Regent Grapevine Plants Treated with Bioproducts

    Get PDF
    The aim of this study was to identify the spores of arbuscular mycorrhizal fungi (AMF) in the rhizosphere of Solaris and Regent grapevine plants grafted onto SO4 rootstock and treated with bioproducts. The bioproducts Ausuma, Bioilsa, manure and BF Ekomix were tested and applied on their own, or combined with standard mineral fertilisation (NPK). The applied bioproducts contributed to an increase in the number of species of mycorrhizal fungi in the rhizosphere soil of the grapevines. The most frequently occurring AMF species was Claroideoglomus claroideum. Biopreparation BF Ekomix was a promisingagent for increasing the number of AMF spores in the rhizosphere of Regent grapevines. In the rhizosphere of Solaris, a positive influence on the number of spores occurred after the application of Bioilsa

    Commissioning of the CMS High Level Trigger

    Get PDF
    The CMS experiment will collect data from the proton-proton collisions delivered by the Large Hadron Collider (LHC) at a centre-of-mass energy up to 14 TeV. The CMS trigger system is designed to cope with unprecedented luminosities and LHC bunch-crossing rates up to 40 MHz. The unique CMS trigger architecture only employs two trigger levels. The Level-1 trigger is implemented using custom electronics, while the High Level Trigger (HLT) is based on software algorithms running on a large cluster of commercial processors, the Event Filter Farm. We present the major functionalities of the CMS High Level Trigger system as of the starting of LHC beams operations in September 2008. The validation of the HLT system in the online environment with Monte Carlo simulated data and its commissioning during cosmic rays data taking campaigns are discussed in detail. We conclude with the description of the HLT operations with the first circulating LHC beams before the incident occurred the 19th September 2008

    B Physics at the Tevatron: Run II and Beyond

    Full text link
    This report provides a comprehensive overview of the prospects for B physics at the Tevatron. The work was carried out during a series of workshops starting in September 1999. There were four working groups: 1) CP Violation, 2) Rare and Semileptonic Decays, 3) Mixing and Lifetimes, 4) Production, Fragmentation and Spectroscopy. The report also includes introductory chapters on theoretical and experimental tools emphasizing aspects of B physics specific to hadron colliders, as well as overviews of the CDF, D0, and BTeV detectors, and a Summary.Comment: 583 pages. Further information on the workshops, including transparencies, can be found at the workshop's homepage: http://www-theory.lbl.gov/Brun2/. The report is also available in 2-up http://www-theory.lbl.gov/Brun2/report/report2.ps.gz or chapter-by-chapter http://www-theory.lbl.gov/Brun2/report

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

    Full text link
    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~pb1^{-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.

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

    Full text link
    The inclusive jet differential cross section has been measured for jet transverse energies, ETE_T, from 15 to 440 GeV, in the pseudorapidity region 0.1η\leq | \eta| \leq 0.7. The results are based on 19.5 pb1^{-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 the Supersymmetric Partner of the Top-Quark in ppˉp \bar{p} Collisions at s=1.8TeV\sqrt{s} = 1.8 {\rm TeV}

    Full text link
    We report on a search for the supersymmetric partner of the top quark (stop) produced in ttˉt \bar{t} events using 110pb1110 {\rm pb}^{-1} of ppˉp \bar{p} collisions at s=1.8TeV\sqrt{s} = 1.8 {\rm TeV} recorded with the Collider Detector at Fermilab. In the case of a light stop squark, the decay of the top quark into stop plus the lightest supersymmetric particle (LSP) could have a significant branching ratio. The observed events are consistent with Standard Model ttˉt \bar{t} production and decay. Hence, we set limits on the branching ratio of the top quark decaying into stop plus LSP, excluding branching ratios above 45% for a LSP mass up to 40 {\rm GeV/c}2^{2}.Comment: 11 pages, 4 figure

    Search for New Particles Decaying to Dijets at CDF

    Get PDF
    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

    Measurement of the ttˉproductioncrosssectionint\bar{t} production cross section in p\bar{p}collisionsat collisions at \sqrt{s}$ = 1.8 TeV

    Full text link
    We update the measurement of the top production cross section using the CDF detector at the Fermilab Tevatron. This measurement uses ttˉt\bar{t} decays to the final states e+νe+\nu+jets and μ+ν\mu+\nu+jets. We search for bb quarks from tt decays via secondary-vertex identification or the identification of semileptonic decays of the bb and cascade cc quarks. The background to the ttˉt\bar{t} production is determined primarily through a Monte Carlo simulation. However, we calibrate the simulation and evaluate its uncertainty using several independent data samples. For a top mass of 175 GeV/c2GeV/c^2, we measure σttˉ=5.1±1.5\sigma_{t\bar{t}}=5.1 \pm 1.5 pb and σttˉ=9.2±4.3\sigma_{t\bar{t}}=9.2 \pm 4.3 pb using the secondary vertex and the lepton tagging algorithms, respectively. Finally, we combine these results with those from other ttˉt\bar{t} decay channels and obtain σttˉ=6.51.4+1.7\sigma_{t\bar{t}} = 6.5^{+1.7}_{-1.4} pb.Comment: The manuscript consists of 130 pages, 35 figures and 42 tables in RevTex. The manuscript is submitted to Physical Review D. Fixed typo in author lis

    Measurement of Dijet Angular Distributions at CDF

    Get PDF
    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
    corecore