17,068 research outputs found

    New Directions in Data Analysis

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    In the next decade, high energy physicists will use very sophisticated equipment to record unprecedented amounts of data in the hope of making major advances in our understanding of particle phenomena. Some of the signals of new physics will be small, and the use of advanced analysis techniques will be crucial for optimizing signal to noise ratio. I will discuss new directions in data analysis and some novel methods that could prove to be particularly valuable for finding evidence of any new physics, for improving precision measurements and for exploring parameter spaces of theoretical models.Comment: 5 pages, 1 Figure, Presented at DPF2000. Proceedings of the American Physical Society DPF2000 Meeting, Columbus, Ohio, to be published in the International Journal of Modern Physics

    Search for the Top Quark at D0 using Multivariate Methods

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    We report on the search for the top quark in proton-antiproton collisions at the Fermilab Tevatron in the di-lepton and lepton+jets channels using multivariate methods. An H-matrix analysis of the e-mu data corresponding to an integrated luminosity of about 13.5 pb-1 yields one event with a likelihood to be a top event (assuming top mass of 180 GeV/c**2) that is 10 times more than WW and 18 times more than Z -> tau tau. A neural network analysis of e+jets channel with about 48 pb-1 of data shows an excess of events in the signal region and yields a cross-section for top-antitop production of 6.7 +/- 2.3(stat.) pb, assuming a top mass of 200 GeV/c**2. A PDE analysis of e+jets data gives results consistent with the above.Comment: 12 pages, http://d0wop.fnal.gov/d0pubs/ppbar95/pushpa.ps Replaced because the first submission was problemati

    Fermilab Collider Run II: Accelerator Status and Upgrades

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    Fermilab will continue to maintain its pre-eminent position in the world of High Energy Physics, with a unique opportunity to make unprecedented studies of the top quark and major discoveries, until the Large Hadron collider (LHC) at CERN becomes operational near the end of the decade. Run II is well underway with major accelerator and detector upgrades since Run I. A program of further upgrades to the accelerator complex will result in an integrated luminosity of 4-8 fb-1 per experiment, by the year 2009.Comment: 12 pages, 6 figures. To be published in the Proceedings of the 15th Topical Conference on Hadron Collider Physics, HCP2004, Michigan State University, East Lansing, MI, June 14-18, 2004 (American Institute of Physics, NY, 2004

    Search for Narrow-Width ttbar Resonances in ppbar Collisions at center of mass energy = 1.8 TeV

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    We present a preliminary result on a search for narrow-width resonances that decay into ttbar pairs using 130 pb^{-1} of lepton plus jets data in ppbar collisions at center of mass energy = 1.8 TeV. No significant deviation from Standard Model prediction is observed. 95% C.L. upper limits on the production cross section of the narrow-width resonance times its branching fraction to ttbar are presented for different resonance masses, M_X. We also exclude the existence of a leptophobic topcolor particle, X, with M_X < 560 GeV/c^2 for a width \Gamma_X = 0.012 M_X.Comment: 3 pages, 1 figure; Submitted for proceedings of 5th International Conference on Quark Confinement and Hadron spectrum, held in Italy, from 11-14 Sep., 200

    Strategy for discovering a low-mass Higgs boson at the Fermilab Tevatron

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    We have studied the potential of the CDF and DZero experiments to discover a low-mass Standard Model Higgs boson, during Run II, via the processes ppˉp\bar{p} -> WH -> ℓνbbˉ\ell\nu b\bar{b}, ppˉp\bar{p} -> ZH -> ℓ+ℓ−bbˉ\ell^{+}\ell^{-}b\bar{b} and ppˉp\bar{p} -> ZH ->ννˉbbˉ\nu \bar{\nu} b\bar{b}. We show that a multivariate analysis using neural networks, that exploits all the information contained within a set of event variables, leads to a significant reduction, with respect to {\em any} equivalent conventional analysis, in the integrated luminosity required to find a Standard Model Higgs boson in the mass range 90 GeV/c**2 < M_H < 130 GeV/c**2. The luminosity reduction is sufficient to bring the discovery of the Higgs boson within reach of the Tevatron experiments, given the anticipated integrated luminosities of Run II, whose scope has recently been expanded.Comment: 26 pages, 8 figures, 7 tables, to appear in Physical Review D, Minor fixes and revision
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