Measurement Of The Production Cross Section Of Pair Of Top Quarks In A Final State With Di Electrons In The Data Collected By D0 Experiment In Run Iia PDF Download
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| Total Pages | : 250 |
| Release | : 2008 |
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Download Measurement of the Production Cross-section of Pair of Top Quarks in a Final State with Di-electrons in the Data Collected by D0 Experiment in Run-IIa Book in PDF, ePub and Kindle
The top quark has been discovered in 1995 by CDF and D0 collaborations in proton-antiproton collisions at the Tevatron. The amount of data recorded by both experiments makes it possible to accurately measure the properties of this very massive quark. This thesis is devoted to the measurement of the top pair production cross-section via the strong interaction, in a final state composed of two electrons, two particle jets and missing transverse energy. It is based on a 1 fb-1 data set collected by the D0 experiment between 2002 and 2006. The reconstruction and identification of electrons and jets is of major importance in this analysis, and have been studied in events where a Z boson is produced together with one or more jets. The Z+jets process is indeed the dominant physics background to top pair production in the dielectron final state. The primary goal of this cross-section measurement is to verify Standard Model predictions. In this document, this result is also interpreted to indirectly extract the top quark mass. Moreover, the cross-section measurement is sensitive to new physics such as the existence of a charged Higgs boson. The selection established for the cross-section analysis has been used to search for a H+ boson lighter than the top quark, where the latter can decay into a W+ or H+ boson and a b quark. The model that has been studied makes the assumption that the H+ boson can only decay into a tau lepton and a neutrino.
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| Total Pages | : 233 |
| Release | : 2010 |
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Download Measurement of Cross Section of Quark Pair Production Top with the D0 Experiment at the Tevatron and Determination the Top Quark Mass Using this Measure Book in PDF, ePub and Kindle
The top quark has been discovered by CDF and D0 experiments in 1995 at the proton-antiproton collider Tevatron. The amount of data recorded by both experiments makes it possible to accurately study the properties of this quark: its mass is now known to better than 1% accuracy. This thesis describes the measurement of the top pair cross section in the electron muon channel with 4, 3 fb−1 recorded data between 2006 and 2009 by the D0 experiment. Since the final state included a muon, improvements of some aspects of its identification have been performed : a study of the contamination of the cosmic muons and a study of the quality of the muon tracks. The cross section measurement is in good agreement with the theoretical calculations and the other experimental measurements. This measurement has been used to extract a value for the top quark mass. This method allows for the extraction of a better defined top mass than direct measurements as it depends less on Monte Carlo simulations. The uncertainty on this extracted mass, dominated by the experimental one, is however larger than for direct measurements. In order to decrease this uncertainty, the ratio of the Z boson and the top pair production cross sections has been studied to look for some possible theoretical correlations. At the Tevatron, the two cross sections are not theoretically correlated: no decrease of the uncertainty on the extracted top mass is therefore possible.
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| Total Pages | : 216 |
| Release | : 2007 |
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Download Measurements of the Top Quark Pair Production Cross Section and an Estimate of the D0 Silicon Detector Lifetime Book in PDF, ePub and Kindle
This thesis presents two measurements of the top quark pair production cross section at (square root)s = 1:96 TeV using data from the D0 experiment. Both measurements are performed in the dilepton final state and make use of secondary vertex b-tagging.
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| Release | : 1974 |
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Download Die Leitstungen des Bundes für Berlin Book in PDF, ePub and Kindle
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| Total Pages | : 121 |
| Release | : 2007 |
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Download First Measurement of Top Quark Pair Production Cross-section in Muon Plus Hadronic Tau Final States Book in PDF, ePub and Kindle
This dissertation presents the first measurement of top quark pair production cross-section in events containing a muon and a tau lepton. The measurement was done with 1 fb−1 of data collected during April 2002 through February 2006 using the D0 detector at the Tevatron proton-antiproton collider, located at Fermi National Accelerator Laboratory (Fermilab), Batavia, Illinois. Events containing one isolated muon, one tau which decays hadronically, missing transverse energy, and two or more jets (at least one of which must be tagged as a heavy flavor jet) were selected. Twenty-nine candidate events were observed with an expected background of 9.16 events. The top quark pair production cross-section is measured to be [sigma](t{bar t}) = 8.0{sub -2.4}{sup +2.8}(stat){sub -1.7}{sup +1.8}(syst) ± 0.5(lumi) pb. Assuming a top quark pair production cross-section of 6.77 pb for Monte Carlo signal top events without a real tau, the measured [sigma] x BR is [sigma](t{bar t}) x BR(t{bar t} → [mu] + [tau] + 2[nu] + 2b) = 0.18{sub -0.11}{sup +0.13}(stat){sub -0.09}{sup +0.09}(syst) ± 0.01(lumi) pb.
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| Total Pages | : 4 |
| Release | : 2009 |
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Download Top Quark Pair Production Cross Section at Tevatron Book in PDF, ePub and Kindle
An overview of the recent measurements of the top antitop quark pair production cross section in proton antiproton collisions at (square root)s = 1.96 TeV in lepton + jets and dilepton final states is presented. These measurements are based on 1-2.8 fb−1 of data collected with the D0 and CDF experiments at the Fermilab Tevatron collider. The cross section is measured with a precision close to 8 % and found to be compatible with the standard model prediction. Interpretations of the cross-section measurements for charge higgs search and for top quark mass measurement are also discussed.
| Author | : Suharyo Sumowidagdo |
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| Release | : 2008 |
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Download First Measurement of Top Quark Pair Production Cross-section in Muon Plus Hadronic Tau Final States Book in PDF, ePub and Kindle
ABSTRACT: This dissertation presents the first measurement of top quark pair production cross-section in events containing a muon and a tau lepton. The measurement was done with 1 inverse femtobarn of data collected during April 2002 through February 2006 using the D0 detector at the Tevatron proton-antiproton collider, located at Fermi National Accelerator Laboratory (Fermilab), Batavia, Illinois. Events containing one isolated muon, one tau which decays hadronically, missing transverse energy, and two or more jets (at least one of which must be tagged as a heavy flavor jet) were selected. Twenty-nine candidate events were observed with an expected background of 9.16 events. The top quark pair production cross-section is measured to be sigma(ttbar) = 8.0 +2.8 -2.4 (stat) +1.8 - 1.7(syst) +/- 0.5 (lumi) pb. Assuming a top quark pair production cross-section of 6.77 pb for Monte Carlo signal top events without a real tau, the measured sigma (ttbar)xBR(ttbar -> muon + tau + 2neutrino + 2b) sigma(ttbar)x BR(ttbar -> muon + tau + 2neutrino + 2b) = 0.18 +0.13 - 0.11 (stat) +0.09 -0.09 (syst) +/- 0.01 (lumi) pb.
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| Release | : 1997 |
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Download Physics of the Top Quark at D0 New Measurement of the Production Cross Section and Mass Book in PDF, ePub and Kindle
We present a measurement of the t{anti t} production cross section in p{anti p} collisions at √s = 1.8 TeV and a measurement of top quark mass m{sub t} by the D0 experiment at the Fermilab Tevatron. The measurements are based on the data from the 1992- 1996 run during which the D0 detector was exposed to the integrated luminosity of approximately 125 pb−1. We observe 39 t{anti t} candidate events in the dilepton and lepton+jets decay channels with an expected background of 13.7 ± 2.2 events. We measure the top quark mass m{sub t} using a two constraint fit to m{sub t} in t{anti t} → bW {anti b}W− final states with one W decaying to q{anti q} and the other to e? or??. Events are binned in the fit mass versus a measure of probability for events to be the signal rather than a background. Likelihood fits to the data yield m{sub t} = 173.3 ± 5.6 (stat) ± 6.2 (syst) GeV/c2. For this mass we measure the t{anti t} production cross section to be 5.5 ± 1.8 pb.
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| Release | : 2001 |
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Download Top Production at Book in PDF, ePub and Kindle
We report an updated measurement of the top quark production cross section in[ital p][ital[anti p]] collisions at[radical]s= 1.8 TeV by the D[null] experiment at the Fermilab Tevatron. We also present a measurement of the top quark mass. The data set used for these measurements corresponds to approximately 100 pb[sup -1], almost the entire data sample collected by the D[null] experiment during the Run I of the Fermilab Tevatron. We observe 37 events with an expected background of 13.4[+-]3.0 events. We measure the mass of the top quark to be 170[+-]15([ital stat])[+-]10([ital syst.]) GeV/c[sup 2]. At this mass we find the top production cross section to be 5.2[+-]1. 8 pb.
| Author | : Wolfgang Wagner |
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| Release | : 2003 |
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Download Top Quark Cross-section Measurements at the Tevatron Book in PDF, ePub and Kindle
Run II of the Tevatron collider at Fermilab is well under way and data samples larger than those of Run I are at hand. In this contribution the author summarizes the current status of cross-section measurements for top-quark pair (t{bar t}) production at the CDF and D0 experiments.
