2,041 research outputs found

    Top Quark Mass Measurements at CDF

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    Recent measurements of the mass of the top quark are presented using 162 pb-1 of data of ppbar collisions at sqrt(s)=1.96 TeV collected by the CDF detector at the Tevatron collider during Run II. The analyses focus on the semi-leptonic decay mode with one or two identified bottom quarks. The Template Method reconstructs the invariant mass of the top quark in each event. The Multivariate Template Method enhances this approach by adding information on the event topology. The Dynamical Likelihood Method discriminates between possible mass values using top quark decay observables and attempts to use the maximum amount of information on top quarks provided by the Standard Model. All three methods produce similar results. The Dynamical Likelihood Method yields a top quark mass of 177.8+-4.5/5.0(stat)+-6.2(sys)GeV/c^2.Comment: 4 pages, 3 figures. Referee's comments included. To appear in the proceedings of the 6th International Conference on Hyperons, Charm and Beauty Hadrons, June 27 - July 03, 2004, Chicago, IL, US

    Tests of QCD in W and Z Production at Tevatron

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    We present measurements of the production cross sections times leptonic branching fractions and the transverse momentum distributions of WW and ZZ bosons in ppˉp\bar{p} collisions at s=1.8\sqrt{s}=1.8 TeV using data collected with the D{\O}detector at the Fermilab Tevatron ppˉp\bar{p} collider. A preliminary measurement of the WW charge asymmetry is also presented.Comment: 25 pages in a uucoded PS fil

    Support Vector Machines in Analysis of Top Quark Production

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    Multivariate data analysis techniques have the potential to improve physics analyses in many ways. The common classification problem of signal/background discrimination is one example. The Support Vector Machine learning algorithm is a relatively new way to solve pattern recognition problems and has several advantages over methods such as neural networks. The SVM approach is described and compared to a conventional analysis for the case of identifying top quark signal events in the dilepton decay channel amidst a large number of background events.Comment: 8 pages, 8 figures, to be published in the proceedings of the "Advanced Statistical Techniques in Particle Physics" conference in Durham, UK (March, 2002

    High-t Diffraction at HERA

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    The double dissociation photoproduction cross section for the process gamma p -> XY, in which the systems X and Y are separated by a large rapidity gap, is measured at large 4-momentum transfer squared |t| > 20 GeV^2 by the H1 Collaboration at HERA. This measurement provides for the first time a direct measurement of the energy dependence of the gap production process at high |t|.Comment: 3 pages, 2 figures, Talk presented at DIS99, Zeuthen, German

    Inclusive Jet Cross Sections in pˉp\bar{p}p Collisions at s\sqrt{s}= 630 and 1800 GeV

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    We have made a precise measurement of the inclusive jet cross section at s\sqrt{s}=1800 GeV. The result is based on an integrated luminosity of 92 pb^{-1} collected at the Fermilab Tevatron pˉp\bar{p}p Collider with the D\O detector. The measurement is reported as a function of jet transverse energy (60 GeV <= E_{T} < 550 GeV), and in the pseudorapidity intervals |\eta| <= 0.5 and 0.1 <= |\eta| <= 0.7. A preliminary measurement of the pseudorapidity dependence of inclusive jet production (|\eta| <= 1.5) is also discussed. The results are in good agreement with predictions from next-to-leading order (NLO) quantum chromodynamics (QCD). D\O has also determined the ratio of jet cross sections at s\sqrt{s}=630 GeV and s\sqrt{s}=1800 GeV (|\eta| <= 0.5). This preliminary measurement differs from NLO QCD predictions.Comment: Submitted to the International Europhysics Conference on High Energy Physics, EPS-HEP99, 15-21 July, 1999, Tampere, Finlan

    Tests of QCD in W and Z production at Tevatron

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    We present measurements of the production cross sections times leptonic branching fractions and the transverse momentum distributions of W and Z bosons in p\bar{p} collisions at \sqrt{s}=1.8~TeV using data collected with the D\O\ detector at the Fermilab Tevatron p\bar{p} collider. A preliminary measurement of the W charge asymmetry is also presented

    Criminal law governing juvenile delinquency in Iran, Germany, and the United Nations : with an empirical survey on attitudes of elites to juvenile criminal law conducted in Iran

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    Juvenile delinquents have always been of special interest to legal practitioners and scholars of law and law-related disciplines, such as criminology, striving to determine how they should be protected by law. Enacting a differentiated law in both substantive and procedural criminal law can be the first step in protecting them. If juvenile substantive criminal law, as the normative section of criminal justice, is defective, then justice cannot be recovered by means of procedural criminal law and through due process. Furthermore, in recent decades, respect for basic rights of juveniles and the importance of criminological research in this field have become major themes in international discourse, initiating a movement toward the recognition and implementation of common, minimum standards of juvenile justice. Germany has recognized these international standards, and Iran has recently paid more attention to such measures in the formulation of its juvenile justice rules. Due to a number of clashes between Islamic Law, customary law, and international obligations, however, Iran has not yet found a definite, integrative strategy for the treatment of juvenile delinquents. The theoretical part of this book investigates – historically and comparatively – the criminal law governing juvenile delinquency in Iran, Germany, and the United Nations. It introduces a model for reforming the structure of Iran’s juvenile criminal law, which has lost touch with the country’s social realities. The empirical part of this study analyzes the public attitudes of the elites toward juvenile justice in Iran, which generally prove to be supportive of international standards

    Identifying the Most Important Organizational barriers of Participation in Keshavarzi Bank in View of Staff of Branches: Case Study of Tehran City

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    System of offers follows main goal of human resource development. In fact, presenting system of offers is considered as a way for growth of human resource and optimum utilization of resources, and consequently development of organization. At this level, most appropriate ideas are sparked in the mind. The human can be idea-creator just when his mind is deeply involved with the problem, and this mental challenge is applicable just with deep sense of responsibility. In this regard, the current study is aimed at identifying the most important organizational barriers of participation in Keshavarzi bank in view of staff of branches; also, the methodology used is of descriptive-survey type. Generally, the research findings indicate that set up of this system is influential in Keshavarzi bank, and the staff are not much satisfied with its implementation

    SUSY-QCD corrections in the squark-gluino sector

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    A status report is given of the calculations of next-to-leading-order (N=1N=1) supersymmetric QCD corrections to the production of squarks and gluinos in ppˉ/ppp\bar{p}/pp collisions. The implementation of these SUSY-QCD corrections leads to more stable theoretical predictions and to a substantial increase of the production cross-sections. In addition we give a discussion of the use of the MS‾\overline{MS} scheme for renormalizing the coupling constants in the QCD sector of (N=1N=1) supersymmetric theories.Comment: 6 two-column pages, tar'ed gzip'ed uuencoded files, LaTeX, 7 Encapsulated Postscript figures, uses epsfig and espcrc2. To appear in the proceedings of the 1996 Zeuthen Workshop on Elementary Particle Theory: "QCD and QED in Higher Orders", J.Bl\"umlein, F.Jegerlehner, and T.Riemann eds. Complete postscript file available at http://rulgm4.LeidenUniv.nl/preprints.htm
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