18,893 research outputs found

    Top quark production cross-section at the Tevatron Run 2

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    The top quark pair production cross-section σttˉ{\sigma}_{t\bar{t}} has been measured in ppˉp\bar{p} collisions at center of mass energies of 1.96 TeV using Tevatron Run 2 data. In the begining of Run 2 both CDF and D\O\ σttˉ\sigma_{t\bar{t}} measurements in the {\it dilepton} channel $t\bar{t}{\to}WbW\bar{b}{\to}\bar{\ell}{\nu}_{\ell}b{\ell}^{'}\ bar{\nu}_{{\ell}^{'}}\bar{b}andintheleptonplusjetschannel and in the {\it lepton plus jets} channel t\bar{t}{\to}WbW\bar{b}{\to}q\bar{q}^{'}b{\ell}\bar{\nu}_{\ell }\bar{b}+\bar{\ell}{\nu}_{\ell}bq\bar{q}^{'}\bar{b}$ agree with the NLO (Next-to-Leading-Order) theoretical predictions. The presence of a top signal in Tevatron data has been reestablished.Comment: 4 pages, 3 figure

    Utility analysis : current trends and future directions.

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    Utility analysis procedures offer organizational decision-makers useful information regarding the relative values of different interventions. Years of research have resulted in a number of practically viable utility models and extensions. There is a continued need for research to examine the accuracy of utility estimates and to further compare the different models. A more recent research concern is that of low levels of acceptance of utility analysis results by practitioners. Many researchers are turning their attention to ways in which this acceptance may be increased. This article reviews different utility models as well as a number of important extensions. It then discusses current utility analysis issues, such as the aforementioned acceptance problem and the introduction of a multi-attribute utility model. The article concludes with suggestions for future utility analysis researchUtility theory; Mathematical models; Decision making;

    Experimental determination of the b quark mass in DELPHI

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    The running mass of the b quark as defined in the MS-bar renormalization scheme, m_b, was measured at the M_Z scale using 2.8 million hadronic Z^0 decays collected by the DELPHI experiment at LEP. The result is m_b(M_Z) = 2.67 +- 0.25 (stat.) +- 0.34 (frag.) +- 0.27(theo.) GeV/c^2 which differs from that obtained at the Upsilon scale, by m_b(M_\Upsilon/2)-m_b(M_Z) = 1.49 +- 0.52 GeV/c^2. This measurement, performed far from the bbˉb\bar{b} production threshold, provides the first experimental observation of the running of the quark masses.Comment: Talk given at the QCD 97 conference held in Montpellier, July 1997. Also available here http://hep.ph.liv.ac.uk/~martis