Download or read book A Measurement of the T Anti t Production Cross section in Proton Anti proton Collisions at u221A s written by and published by . This book was released on 2004 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Measurement of the T Anti t Production Cross Section in P Anti p Collisions at u221A s written by and published by . This book was released on 2004 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book A Measurement of the T Anti t Production Cross section in Proton Anti proton Collisions at S 1 2 written by Markus Klute and published by . This book was released on 2004 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book A Measurement of the T Anti t Production Cross section in Proton Anti proton Collisions at S 1 2 written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract Not Provided.

Download or read book Measurements of the T bar t Production Cross Section at u221A s written by and published by . This book was released on 2005 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Measurement of the P Anti p T Anti t Production Cross Section at S written by and published by . This book was released on 2006 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book A Measurement of the T T bar Production Cross Section in Proton antiproton Collisions at Sqrt s written by Markus Klute and published by . This book was released on 2004 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement of the P Anti p T Anti t Production Cross Section at S 1 2 written by and published by . This book was released on 2006 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 [sigma]{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.

Download or read book A Measurement of the Production Cross Section of Tt Pairs in Proton antiproton Collisions at square Root s written by Henri Bachacou and published by . This book was released on 2004 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurements of Top Quark Pair Production Cross Section in Proton Anti proton Collisions at u221A s written by and published by . This book was released on 2009 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book 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 published by . This book was released on 2005 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Measurement of the T Anti t Production Cross Section in P Anti p Collisions at S 1 2 written by Heather Lynn Ray and published by . This book was released on 2004 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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{bar t} production cross section using 107.9 pb{sup -1} of p{bar p} collisions at {radical}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{bar t} production in the ''lepton plus jets'' final state in which one of the W bosons from the t{bar 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{bar t} events relative to the background through identification of the bottom quark from its measurable lifetime. The t{bar t} production cross section is measured to be {sigma}{sub t{bar t}} = 4.5 {+-} 1.4(stat) {+-} 0.8(sys) pb.

Download or read book Measurement of Top Anti top Cross Section in Proton Anti proton Collider at u221A s written by and published by . This book was released on 2005 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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).

Download or read book A Measurement of the Tt Production Cross Section in Proton antiproton Collisions at square Root S written by Markus Klute and published by . This book was released on 2004 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Measurement of the Top antitop Production Cross Section in Proton antiproton Collisions at Center of Mass Energy written by Ulysses Allen Grundler and published by ProQuest. This book was released on 2008 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: I present a measurement of the tt¯ production cross section at s = 1.96 TeV using 2034 pb-1 of CDF Run II data using events with a high transverse momentum electron or muon, three or more jets, and missing transverse energy. The measurement assumes a t → Wb branching fraction of 100 percent. Events consistent with tt¯ decay are found by identifying jets containing heavy-flavor semileptonic decays to muons. The dominant backgrounds are evaluated directly from the data. Based on 248 candidate events and an expected background of 86.8+/-5.6 events, I measure a production cross section of 8.7+/-1.1+0.9-0.8+/-0.6 pb, in agreement with the Standard Model.

Download or read book 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 published by . This book was released on 2007 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book A Measurement of the Production Cross Section of Top antitop Pairs in Proton antiproton Collisions at a Center of Mass of 1 96 TeV Using Secondary Vertexb tagging written by Henri Bachacou and published by . This book was released on 2004 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: A measurement of the t{bar t} pair production cross section is presented using 162 pb{sup -1} of data collected by the CDF experiment during Run II at the Tevatron. t{bar t} events in the lepton+jets channel are isolated by identifying electrons and muons, reconstructing jets and transverse missing energy, and identifying b jets with a secondary vertex tagging algorithm. The efficiency of the algorithm is measured in a control sample using a novel technique that is less dependent on the simulation. For a top quark mass of 175 GeV/c{sup 2}, a cross section of {sigma}{sub t{bar t}} = 5.6{sub -1.1}{sup +1.2}(stat.){sub -0.6}{sup +0.9}(syst.)pb is measured.