Measurement of Cross-section (p Anti-p --] Z0) X BF (Z0 --] Tau Anti-tau) at S**(1/2)
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Published: 2006
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Author: Silke Duensing
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Published: 2004
Total Pages: 114
ISBN-13: 9789090174587
DOWNLOAD EBOOKAuthor: Sebastian Carron Montero
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Published: 2006
Total Pages: 204
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DOWNLOAD EBOOKIn this thesis we present a new technique to analyze events containing two highly energetic leptons, as a probe of the Standard Model. The philosophy is to consider the data in a more global way, as opposed to the more traditional process dependent approach of extracting a given signal over the expected backgrounds by using various kinematical requirements. We use our global technique to simultaneously measure the cross sections of the main Standard Model processes; the t{bar t}, WW and Z → [tau][tau] production from p{bar p} collisions at √s = 1.96 TeV in the CDF detector at Fermilab. We select events by requiring they contain two highly energetic leptons (e[mu], ee, or [mu][mu]), and make no other kinematic requirements, except for the ee and [mu][mu] channels. We then use a likelihood fit of the data in the two-dimensional phase space defined by the missing transverse energy (E{sub T}) and the number of jets in the event (N{sub jet}), to the expected Standard Model distributions, to simultaneously extract the production cross-sections of the main process contributing to our dilepton sample.
Author: Martin Werner Grünewald
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Published: 1993
Total Pages: 266
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DOWNLOAD EBOOKAuthor: Sebastian Carron Montero
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Published: 2006
Total Pages: 366
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Published: 2008
Total Pages: 10
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Published: 1996
Total Pages: 283
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DOWNLOAD EBOOKIn this dissertation, a measurement of the partial decay width of the process Z0 → [tau]+[tau]- using data collected during 1993 and 1994 at the OPAL detector at CERN is described. The cross sections of this process at three center-of-mass energies near the Z0 resonance were determined, and from a fit to those cross sections, the mass of the Z0, its total decay width and its partial decay width into [tau]+[tau]- final states were determined as MZ = 91.183 ± 0.020 GeV, [Gamma]tot = 2.514 ± 0.018 GeV and [Gamma][tau][tau] = 84.54 ± 0.59 MeV. Using published results for MZ, and [Gamma]tot with higher accuracy, a value for the partial decay width of [Gamma][tau][tau] = 84.02 ± 0.20 MeV was obtained. Further using published results for the decay width of the Z0 into quark pair final states, the invisible decay width of the Z0 was determined as [Gamma]inv = 496.9 ± 4.1 MeV, and the number of neutrino generations was determined as Nv = 2.974 ± 0.025(exp) ± 0.007 (mtop, MHiggs). All results were found to be in good agreement with the Standard Model predictions and were consistent with the assumption of lepton universality within the Standard Model framework.
Author: Lucio Cerrito
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Published: 2005
Total Pages: 4
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DOWNLOAD EBOOKWe present two measurements of the t{bar t} production cross section in collisions of protons and antiprotons at {radical}s = 196 TeV. We analyze a dataset of 310 {+-} 20 pb{sup -1} collected with the CDF 2 detector. In the first measurement, we select events with six to eight jets, at least one of which having a displaced secondary vertex, little or no missing transverse energy and optimized kinematical criteria consistent with the t{bar t} all-hadronic decay channel. In the second measurement, we select events with four or more jets, at least one of which having a displaced secondary vertex, high missing transverse energy, and optimized kinematical criteria consistent with the decay of t{bar t} to {tau}+jets. The averaged t{bar t} production cross section, determined from six different measurements using the CDF 2 detector in the dilepton, lepton+jets and all-hadronic decay channels, is also calculated to be {sigma}{sub t{bar t}} = 7.1 {+-} 0.6(stat) {+-} 0.7(syst) {+-} 0.4(lumi) pb, in agreement with the prediction of the standard model.
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Published: 2008
Total Pages: 10
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Published: 2005
Total Pages: 72
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