Measurement of the Top Anti-top Quark Pair Production Cross-section in the [tau] + Jets Channel at [square Root of S] PDF Download
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![Measurement of the Top Anti-top Quark Pair Production Cross-section in the [tau] + Jets Channel at [square Root of S] PDF](https://books.google.com/books/content/images/frontcover/eUEsrgEACAAJ?fife=w150-h200)
Author: Teeba Rashid
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ISBN:
Category : Hadron interactions
Languages : en
Pages : 195
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![Measurement of the Top Anti-top Quark Pair Production Cross-section in the [tau] + Jets Channel at [square Root of S] PDF](https://books.google.com/books/content/images/frontcover/eUEsrgEACAAJ?fife=w80-h100)
Author: Teeba Rashid
Publisher:
ISBN:
Category : Hadron interactions
Languages : en
Pages : 195
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Author:
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ISBN:
Category :
Languages : en
Pages : 229
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In this thesis, we present the first exclusive observation of the t-t → hadronic [tau] + jets decay channel. Using these events, we measure the t-t pair production cross section and the top quark mass in 2.2 fb-1 of data collected with the Collider Detector at Fermilab (CDF). The Tevatron accelerator at Fermilab provides collisions of protons and anti-protons at a center-of-mass energy of √s = 1.96 TeV and is one of only two accelerators in the world with enough energy to produce top quarks. With a branching fraction of nearly 10%, the hadronic [tau] + jets decay channel is the third largest t-t decay mode, and it has only been minimally explored. This the first measurement of the t-t pair production cross section in this decay channel at CDF and the first measurement of the top quark mass in this decay channel in the world. The analysis introduces a new method to recover the total momentum of the [nu] produced in the [tau] decay and an artificial neural network to reduce the contribution from the largest background source, QCD multijet background. The t-t pair production cross section is extracted by minimizing a negative log likelihood function which compares the number of observed events to the number of expected events for a given t-t cross section. The top quark mass is extracted by minimizing a negative log likelihood function built from signal and ii background probabilities which are based on the matrix elements for t-t production and decay and W + 4 parton production, respectively. Using events selected with exactly 1 hadronically decaying [tau], exactly 4 jets with at least 1 identified as having originated from a b quark, and large missing transverse energy, we measure the t-t pair production cross section to be 8.8 ± 3.3 (stat.) ± 2.2 (syst.) pb and the top quark mass to be 172.7±9.3 (stat.) ±3.7 (syst.) GeV. We find both values to be in good agreement with previous measurements in other t-t decay channels, and the cross section to be consistent with next-to-leading order theoretical predictions.
Author: Daryl Curtis Hare
Publisher:
ISBN:
Category : Hadron colliders
Languages : en
Pages : 212
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Author:
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Category :
Languages : en
Pages : 31
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The top quark pair production cross section is measured in dilepton events with one electron or muon, and one hadronically decaying tau lepton from the decay t anti-t to (l nu(l)) (tau nu(tau)) b anti-b, where l can be either an electron or a muon. The data sample corresponds to an integrated luminosity of 2.0 inverse femtobarns for the electron channel and 2.2 inverse femtobarns for the muon channel, collected by the CMS detector at the LHC. This is the first measurement of the t anti-t cross section explicitly including tau leptons in proton-proton collisions at sqrt(s)=7 TeV. The measured value sigma(t anti-t) = 143 +/- 14 (stat.) +/- 22 (syst.) +/- 3 (lumi.) pb is consistent with the standard model predictions.
Author:
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Category :
Languages : en
Pages : 4
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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.
![Measurement of [sigma] X Br(W [approaches] [tau] + [upsilon] + Jets) Via Precision Tracking in P̄p Collisions at [square Root of S] PDF](https://books.google.com/books/content/images/frontcover/s7UeAQAAMAAJ?fife=w80-h100)
Author: Robert Andrew Dunn
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ISBN:
Category :
Languages : en
Pages : 326
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Author: Bin Guo
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ISBN:
Category :
Languages : en
Pages :
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We present a measurement of the top anti-top quark (ttbar)production cross section in the dilepton final states from proton-proton collisions at a center of mass energy at 7 TeV at the LHC. A b-tagging algorithm based on tracks displaced from the event interaction vertex is applied to identify bottom quark jets from top quark decay and reject background events. Given the relatively pure sample of bottom quark jets in ttbar dilepton final states, a new technique to measure in-situ the b-tagging efficiency is introduced that uses the distribution of the number of observed b-tagged jets. We present results with data collected at the ATLAS detector in 2010 with an integrated luminosity of 35 pb-1. The measured ttbar cross section is 176 +22/-21 (stat.) ± 20 (syst.) ± 6 (lum.) pb in the dilepton channel. We will also discuss the future prospects of this measurement.
Author: Tobias F. Golling
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ISBN:
Category :
Languages : en
Pages : 299
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Two alternative measurements of the t{bar t} production cross section at {radical}s = 1.96 TeV in proton-antiproton collisions in the lepton+jets channel are presented. The t{bar t} production cross section is extracted by combining the kinematic event information in a multivariate discriminant. The measurement yields {sigma}{sub p{bar p} {yields} t{bar t} + x} = 5.13{sub -1.57}{sup +1.76}(stat){sub -1.10}{sup +0.96}(syst) {+-} 0.33 (lumi) pb in the muon+jets channel, using 229.1 pb{sup -1}, and in the combination with the electron+jets channel 226.3 pb{sup -1} {sigma}{sub p{bar p} {yields} t{bar t} + x} = 6.60{sub -1.28}{sup +1.37}(stat){sub -1.11}{sup +1.25}(syst) {+-} 0.43 (lumi) pb. The second measurement presented reconstructs explicitly secondary vertices to d lifetime b-tagging. The measurement combines the muon+jets and the electron+jets channel, using 158.4 pb{sup -1} and 168.8 pb{sup -1}, respectively: {sigma}{sub p{bar p} {yields} t{bar t} + x} = 8.24{sub -1.25}{sup +1.34}(stat){sub -1.63}{sup +1.89}(syst) {+-} 0.54 (lumi) pb.
Author: Florian Christoph Maria Fischer
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ISBN:
Category :
Languages : en
Pages :
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Author: Ahmed A. Hasib
Publisher:
ISBN:
Category : Collisions (Nuclear physics)
Languages : en
Pages : 530
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