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 Recueil Festival d Edimbourg 1947 written by and published by . This book was released on 1949 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book Measurement of the Single Top Production Cross Section in Proton antiproton Collisions at 1 96 TeV written by and published by . This book was released on 2010 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes a search for singly produced top quarks via an electroweak vertex in head-on proton-antiproton collisions at a center of mass energy of √s = 1.96 TeV. The analysis uses a total of 2.3 fb−1 of data collected with the D0 detector at Fermilab, corresponding to two different run periods of the Tevatron collider. Two channels contribute to single top quark production at the Tevatron, the s-channel and the t-channel. In the s-channel, a virtual W boson is produced from the aniquilation of a quark and an antiquark and a top and a bottom quarks are produced from the W decay. The top quark decays almost exclusively into a W boson and a bottom quark. Final states are considered in which the W boson decays leptonically into an electron or a muon plus a neutrino. Thus, at the detector level, the final state characterizing the s-channel contains one lepton, missing energy accounting for the neutrino, and two jets from the two bottom quarks. In the t-channel, the final state has an additional jet coming from a light quark. Clearly, a precise reconstruction of the events requires a precise measurement of the energy of the jets. A multivariate technique, Bayesian neural networks, is used to extract the single top signal from the overwhelming background still left after event selection. A Bayesian likelihood probability is then computed to measure the single top cross section. Assuming the observed excess is due to single top events, the measured single top quark production cross section is [sigma](p{bar p} → tb + X, tqb + X) = 4.70{sub -0.93}{sup +1.18} pb. The observed excess is associated with a p-value of (3.2 ± 2.3) x 10−8, assuming the background-only hypothesis. This p-value corresponds to an excess over background of 5.4 standard deviations for a Gaussian density. The p-value computed using the standard model signal cross section of 3.46 pb is (22.7 ± 0.6) x 10−6, corresponding to an expected significance of 4.08 standard deviations.
Download or read book Measurements of the B Production Cross Section in Proton antiproton Collisions at Center of Mass Energy written by James Alexander Kraus and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of the Top antitop Production Cross Section in Pp Collisions at Sqrt s written by and published by . This book was released on 2011 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: A measurement of the top-antitop production cross section in proton-proton collisions at a centre-of-mass energy of 7 TeV has been performed at the LHC with the CMS detector. The analysis uses a data sample corresponding to an integrated luminosity of 36 inverse picobarns and is based on the reconstruction of the final state with one isolated, high transverse-momentum electron or muon and three or more hadronic jets. The kinematic properties of the events are used to separate the top-antitop signal from W+jets and QCD multijet background events. The measured cross section is 173 + 39 - 32 (stat. + syst.) pb, consistent with standard model expectations.
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 Vertex B tagging 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 Top Quark anti top Quark Production Cross Section Measurement Using Soft Electron Tagging in Proton anti proton Collisions at Center of Mass Energy written by John Paul Chou and published by . This book was released on 2008 with total page 474 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 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 Measurements of the Top Anti top Production Cross Section at S 1 2 written by Joseph Francis Kozminski 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 {radical}s = 1.96 TeV using 243 pb{sup -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 {sigma}{sub t{bar t}} = 14.9{sub -7.0}{sup +9.4}(stat){sub -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 Proton antiproton Total Cross Section at Center of Mass Energy of 1800 GEV written by Carlos Avila and published by . This book was released on 1997 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book First Measurement of the Cross Section for Top Quark Pair Production in Proton Proton Collisions at sqrt s written by and published by . This book was released on 2011 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first measurement of the cross section for top-quark pair production in pp collisions at the LHC at center-of-mass energy sqrt(s)= 7 TeV has been performed using 3.1 {\pm} 0.3 inverse pb of data recorded by the CMS detector. This result utilizes the final state with two isolated, highly energetic charged leptons, large missing transverse energy, and two or more jets. Backgrounds from Drell-Yan and non-W/Z boson production are estimated from data. Eleven events are observed in the data with 2.1 {\pm} 1.0 events expected from background. The measured cross section is 194 {\pm} 72 (stat.) {\pm} 24 (syst.) {\pm} 21 (lumi.) pb, consistent with next-to-leading order predictions.
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 Measurement of the Front Back Asymmetry in Top antitop Quark Pairs Produced in Proton antiproton Collisions at Center of Mass Energy written by Thomas A. Schwarz and published by . This book was released on 2006 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quarks, along with leptons and force carrying particles, are predicted by the Standard Model to be the fundamental constituents of nature. In distinction from the leptons, the quarks interact strongly through the chromodynamic force and are bound together within the hadrons. The familiar proton and neutron are bound states of the light ''up'' and ''down'' quarks. The most massive quark by far, the ''top'' quark, was discovered by the CDF and D0 experiments in March, 1995. The new quark was observed in p{bar p} collisions at 1.8 TeV at the Fermilab Tevatron. The mass of the top quark was measured to be 176 {+-} 13 GeV/c{sup 2} and the cross section 6.8{sub -2.4}{sup +3.6} pb. It is the Q = 2/3, T{sub 3} = +1/2 member of the third generation weak-isospin doublet along with the bottom quark. The top quark is the final Standard Model quark to be discovered. Along with whatever is responsible for electroweak symmetry breaking, top quark physics is considered one of the least understood sectors of the Standard Model and represents a front line of our understanding of particle physics. Currently, the only direct measurements of top quark properties come from the CDF and D0 experiments observing p{bar p} collisions at the Tevatron. Top quark production at the Tevatron is almost exclusively by quark-antiquark annihilation, q{bar q} {yields} t{bar t} (85%), and gluon fusion, gg {yields} t{bar t} (15%), mediated by the strong force. The theoretical cross-section for this process is {sigma}{sub t{bar t}} = 6.7 {+-} 0.8 pb for m{sub t} = 175 GeV/c{sup 2}. Top quarks can also be produced at the Tevatron via q{bar b}{prime} {yields} tb and qg {yields} q{prime}tb through the weak interaction. The cross section for these processes is lower (3pb) and the signal is much more difficult to isolate as backgrounds are much higher. The top quark is predicted to decay almost exclusively into a W-boson and a bottom quark (t {yields} Wb). The total decay width t {yields} Wb is {Lambda} = 1.50 GeV. This corresponds to an incredibly short lifetime of 0.5 x 10{sup -24} seconds. This happens so quickly that hadronization and bound states do not take place, which leads to the interesting consequence that the top quark spin information is passed to the decay products.
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 Measurement of the T Anti t Production Cross Section in P Anti p Collisions at S 1 2 written by and published by . This book was released on 2005 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a measurement of the top quark pair (t{bar t}) production cross section ([sigma]{sub t{bar t}}) in p{bar p} collisions at a center-of-mass energy of 1.96 TeV using 230 pb1 of data collected by the D0 detector at the Fermilab Tevatron Collider. We select events with one charged lepton (electron or muon), large missing transverse energy, and at least four jets, and extract the t{bar t} content of the sample based on the kinematic characteristics of the events. For a top quark mass of 175 GeV, we measure [sigma]{sub t{bar t}} = 6.7{sub -1.3}{sup +1.4}(stat){sub -1.1}{sup +1.6}(syst) ± 0.4(lumi)pb, in good agreement with the standard model prediction.
Download or read book First Measurement of the Top quark Pair Production Cross Section in Proton proton Collisions at the Center of Mass Energy of 7 TeV written by Puneeth D. Kalavase and published by . This book was released on 2011 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first measurement of the cross section for top-quark pair production in proton-proton collisions at the Large Hadron Collider at center-of-mass energy of 7 TeV has been performed using a data sample corresponding to an integrated luminosity of 3 pb-1 recorded by the CMS detector. This result utilizes the final state with two isolated, highly energetic charged leptons, large missing transverse energy, and two or more jets. Backgrounds from Drell-Yan and non-W/Z boson production are estimated from data. Eleven events are observed in the data with 2.1+/-1.0 events expected from background. The measured cross section is 194+/-72 (statistical) +/-24 (systematic) +/-21 (luminosity) pb. The result is consistent with next-to-leading order theoretical predictions.
