A Measurement Of The T Anti T Production Cross Section In Proton Anti Proton Collisions At U221a S
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A Measurement Of The T Anti T Production Cross Section In Proton Anti Proton Collisions At U221a S
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Author :
language : en
Publisher:
Release Date : 2004
A Measurement Of The T Anti T Production Cross Section In Proton Anti Proton Collisions At U221a S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with categories.
A preliminary measurement of the t$ar{t}$ production cross section at √s = 1.96 TeV is presented. The ?-plus-jets final state is analyzed in a data sample of 94 pb-1 and a total of 14 events are selected with a background expectation of 11.7 ± 1.9 events. The measurement yields: ?p$ar{p}$ → t$ar{t}$ + X} = 2.4$+4.2top{-3.5}$(stat.)$+2.5top{-2.6}$(syst.) ± 0.3(lumi.) pb. The analysis, being part of a larger effort to re-observe the top quark in Tevatron Run II data and to measure the production cross section, is combined with results from all available analyses channels. The combined result yields: ? p$ar{p}$ → t$ar{t}$ + X = 8.1$+2.2top{-2.0}$(stat.)$+1.6top{-1.4}$(syst.) ± 0.8(lumi.) pb.
Measurement Of The T Anti T Production Cross Section In P Anti P Collisions At U221a S
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Author :
language : en
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Release Date : 2004
Measurement Of The T Anti T Production Cross Section In P Anti P Collisions At U221a S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with categories.
The direct observation of the top quark was first achieved at the Tevatron proton anti-proton collider at Fermilab. This discovery completed the third generation quark sector where the top quark is expected to accompany the bottom quark in the weak isospin doublet. This dissertation discusses the experimental verification of the production cross section as predicted by the Standard Model. A measurement of the t$ar{t}$ production cross section using 107.9 pb-1 of p$ar{p}$ collisions at √s = 1.96 TeV collected with the Collider Detector at Fermilab between March of 2003 and June of 2003 is presented. The measurement focuses on the t$ar{t}$ production in the ''lepton plus jets'' final state in which one of the W bosons from the t$ar{t}$ decay subsequently decays leptonically to an electron or a muon, and the other decays hadronically. The B-tagging technique which utilizes the precision silicon detector tracking is used to enhance the signal for t$ar{t}$ events relative to the background through identification of the bottom quark from its measurable lifetime. The t$ar{t}$ production cross section is measured to be ?t$ar{t}$ = 4.5 ± 1.4(stat) ± 0.8(sys) pb.
Measurements Of Top Quark Pair Production Cross Section In Proton Anti Proton Collisions At U221a S
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Author :
language : en
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Release Date : 2009
Measurements Of Top Quark Pair Production Cross Section In Proton Anti Proton Collisions At U221a S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
This dissertation presents a new measurement of p$ar{p}$ → t$ar{t}$X production at √s = 1.96 TeV using 974.2 pb-1of data collected with the D0 detector between 2002 and 2006. We focus on the final state where the W boson from one of the top quarks decays into a ? lepton and its associated neutrino, while the other W boson decays into a quark-antiquark pair. We aim to select those events in which the ? lepton subsequently decays hadronically, meaning to one or three charged hadrons, zero or more neutral hadrons and a tau neutrino (the charge conjugate processes are implied in all of the above). The observable signature thus consists of a narrow calorimeter shower with associated track(s) characteristic of a hadronic tau decay, four or more jets, of which two are initiated by b quarks accompanying the W's in the top quark decays, and a large net missing momentum in the transverse plane due to the energetic neutrino-antineutrino pair that leave no trace in the detector media. The preliminary result for the measured cross section is: ?(t$ar{t}$) = 6.9-1.2 +1.2(stat)-0.7+0.8(syst) ± 0.4 (lumi) pb. This indicates that our finding is consistent with the Standard Model prediction.
A Measurement Of The T Anti T Production Cross Section In Proton Anti Proton Collisions At S 1 2
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Author : Markus Klute
language : en
Publisher:
Release Date : 2004
A Measurement Of The T Anti T Production Cross Section In Proton Anti Proton Collisions At S 1 2 written by Markus Klute and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with categories.
A preliminary measurement of the t{bar t} production cross section at {radical}s = 1.96 TeV is presented. The {mu}-plus-jets final state is analyzed in a data sample of 94 pb{sup -1} and a total of 14 events are selected with a background expectation of 11.7 {+-} 1.9 events. The measurement yields: {sigma}{sub p{bar p} {yields} t{bar t} + X} = 2.4{sub -3.5}{sup +4.2}(stat.){sub -2.6}{sup +2.5}(syst.) {+-} 0.3(lumi.) pb. The analysis, being part of a larger effort to re-observe the top quark in Tevatron Run II data and to measure the production cross section, is combined with results from all available analyses channels. The combined result yields: {sigma}{sub p{bar p}} {yields} t{bar t} + X = 8.1{sub -2.0}{sup +2.2}(stat.){sub -1.4}{sup +1.6}(syst.) {+-} 0.8(lumi.) pb.
Measurement Of Top Anti Top Cross Section In Proton Anti Proton Collider At U221a S
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Author :
language : en
Publisher:
Release Date : 2005
Measurement Of Top Anti Top Cross Section In Proton Anti Proton Collider At U221a S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.
Discovery of the top quark in 1995 at the Fermilab Tevatron collider concluded a long search following the 1977 discovery of bottom (b) quark [1] and represents another triumph of the Standard Model (SM) of elementary particles. Top quark is one of the fundamental fermions in the Standard Model of electroweak interactions and is the weak-isospin partner of the bottom quark. A precise measurement of top pair production cross-section would be a test of Quantum Chromodynamics (QCD) prediction. Presently, Tevatron is the world's highest energy collider where protons (p) and anti-protons ($ar{p}$) collide at a centre of mass energy √s of 1.96 TeV. At Tevatron top (t) and anti-top ($ar{t}$) quarks are predominantly pair produced through strong interactions--quark annihilation (≅ 85%) and gluon fusion (≅ 15%). Due to the large mass of top quark, t or $ar{t}$ decays ( ̃10-25 sec) before hadronization and in SM framework, it decays to a W boson and a b quark with ̃100% branching ratio (BR). The subsequent decay of W boson determines the major signatures of t$ar{t}$ decay. If both W bosons (coming from t and $ar{t}$ decays) decay into leptons (viz., eve, ?v? or ?c?) the corresponding t$ar{t}$ decay is called dileptonic decay. Of all dileptonic decay modes of t$ar{t}$, the t$ar{t}$ → WWb$ar{b}$ → eve?v?b$ar{b}$ (e? channel) decay mode has the smallest background contamination from Z0 production or Drell-Yan process; simultaneously, it has the highest BR ( ̃3.16%) [2] amongst all dileptonic decay modes of t$ar{t}$. During Run I (1992-1996) of Tevatron, three e? candidate events were detected by D0 experiment, out of 80 candidate events (inclusive of all decay modes of t$ar{t}$). Due to the rarity of the t$ar{t}$ events, the measured cross-section has large uncertainty in its value (viz., 5.69 ± 1.21(stat) ± 1.04(sys) pb @ √s = 1.8 TeV measured by D0 [3]). This analysis presents a cross section measurement in e? channel utilizing ̃228 pb-1 of data collected by D0 experiment during Tevatron Run II (between June 2002 and April 2004).
A Measurement Of The T Anti T Production Cross Section In Proton Anti Proton Collisions At S 1 2
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Author :
language : en
Publisher:
Release Date : 2006
A Measurement Of The T Anti T Production Cross Section In Proton Anti Proton Collisions At S 1 2 written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with categories.
Abstract Not Provided.
Measurements Of The Top Quark Pair Production Cross Section In Lepton Jets Final States Using A Topological Multivariate Technique As Well As Lifetime B Tagging In Proton Anti Proton Collisions At U221a S
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Author :
language : en
Publisher:
Release Date : 2005
Measurements Of The Top Quark Pair Production Cross Section In Lepton Jets Final States Using A Topological Multivariate Technique As Well As Lifetime B Tagging In Proton Anti Proton Collisions At U221a S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.
Two alternative measurements of the t¯t production cross section at √s = 1.96 TeV in proton-antiproton collisions in the lepton+jets channel are presented. The t¯t production cross section is extracted by combining the kinematic event information in a multivariate discriminant. The measurement yields ?p¯p → t¯t + x = 5.13-1.57+1.76(stat)-1.10+0.96(syst) ± 0.33 (lumi) pb in the muon+jets channel, using 229.1 pb-1, and in the combination with the electron+jets channel (226.3 pb-1) ?p¯p → t¯t + x = 6.60-1.28+1.37(stat)-1.11+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-1 and 168.8 pb-1, respectively: ?p¯p → t¯t + x = 8.24-1.25+1.34(stat)-1.63+1.89(syst) ± 0.54 (lumi) pb.
Measurements Of The T Bar T Production Cross Section At U221a S
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Author :
language : en
Publisher:
Release Date : 2005
Measurements Of The T Bar T Production Cross Section At U221a S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.
The first measurement of the top-antitop production cross section in proton-antiproton collisions at √s = 1.96 TeV using 243 pb-1 of data collected with the D0 detector at Fermilab is presented. In this analysis, only the dielectron final state is considered. Five events are observed, and 0.93 background events are expected. The measured cross section, after accounting for the expected branching ratio to the dielectron channel, is ?t$ar{t}$ = 14.9$+9.4top{-7.0}$(stat)$+2.5top{-1.8}${sup +2.5}(syst) ± 1.0 (lumi) pb, which agrees with the predicted cross section for top quarks with a mass of 175 GeV. In addition, a first-pass at a measurement of the top mass using the neutrino-weighting method is presented. This measurement is also performed in the dielectron channel using the five events observed in the cross section measurement.
A Measurement Of The Top Antitop Production Cross Section In The Dimuon Final State With The D0 Detector For Proton Antiproton Collisions As U221a S
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Author :
language : en
Publisher:
Release Date : 2007
A Measurement Of The Top Antitop Production Cross Section In The Dimuon Final State With The D0 Detector For Proton Antiproton Collisions As U221a S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
A measurement of the top pair production cross section in the dimuon final state for proton-antiproton collisions at √s = 1.96 TeV is presented. Approximately 420 pb-1 of data collected with the Run II D0 detector are used for this measurement. Two data events are observed with a total expected signal plus background yield of 3.6 events. Assuming a top mass of 175 GeV, the measured cross section is: ?t$ar{t}$= 3.13$+4.17top{-2.60}$(stat)$+0.92top{-0.86}$(sys)±0.19(lumi)pb, which is consistent with a NNLO prediction of 6.77 ± 0.42 pb.
Measurement Of The P Anti P T Anti T Production Cross Section At S
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Author :
language : en
Publisher:
Release Date : 2006
Measurement Of The P Anti P T Anti T Production Cross Section At S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with categories.
A measurement of the top quark pair production cross section in proton anti-proton collisions at an interaction energy of √s = 1.96 TeV is presented. This analysis uses 405 pb−1 of data collected with the D0 detector at the Fermilab Tevatron Collider. Fully hadronic t{bar t} decays with final states of six or more jets are separated from the multijet background using secondary vertex tagging and a neural network. The t{bar t} cross section is measured as?{sub t{bar t}} = 4.5{sub -1.9}{sup +2.0}(stat){sub -1.1}{sup +1.4}(syst) ± 0.3(lumi) pb for a top quark mass of m{sub t} = 175 GeV/c2.