Download or read book Study on the Top Quark Pair Production Mechanism in 1 96 TeV Proton antiproton Collisions written by and published by . This book was released on 2008 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of the top quark pair production mechanism in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV is described. The main subjects are the measurements of the top quark pair production cross section, the top quark mass and a search for a new particle decaying to the top quark pair. The analyses are based on 1.9 fb−1 of data collected by the Collider Detector at Fermilab (CDF) Run II experiment between March 2002 and May 2007, using the lepton+jets events. The measured top quark pair production cross section is 8.2 ± 0.5 (stat.) ± 0.8 (syst.) ± 0.5 (lum.) pb, which is slightly higher than the standard model prediction at the top mass of 175 GeV/c2. The top quark mass is an important parameter in the standard model, and also in the experimental studies. The measured top quark mass if 171.6 ± 2.0 (stat.) ± 1.3(syst.) GeV/c2. Finally, they report on a search for a new gauge boson decaying to t{bar t}, which interferes with the standard model gluon in the q{bar q} --> t{bar t} production process. They call such a hypothetical particle a 'Massive Gluon'. The observed t{bar t} invariant mass distribution is consistent with the standard model expectations, and also the measured massive gluon coupling strength with quarks is consistent within a statistical fluctuation of the standard model expectation in the wide range of the massive gluon masses and widths. They set the upper and lower limits on the coupling strength of the massive gluon.
Download or read book Measurement of the Top Quark Pair Production Cross section in Dimuon Final States in Proton antiproton Collisions at 1 96 TeV written by and published by . This book was released on 2008 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt: Particle physics deals with the fundamental building blocks of matter and their interactions. The vast number of subatomic particles can be reduced to twelve fundamental fermions, which interact by the exchange of spin-1 particles as described in the Standard Model (SM) of particle physics. The SM provides the best description of the subatomic world to date, despite the fact it does not include gravitation. Following the relation [lambda] = h/p, where h is Planck's constant, for the examination of physics at subatomic scales with size [lambda] probes with high momenta p are necessary. These high energies are accessible through particle colliders. Here, particles are accelerated and brought to collision at interaction points at which detectors are installed to record these particle collisions. Until the anticipated start-up of the Large Hadron Collider at CERN, the Tevatron collider at Fermilab near Chicago is the highest energy collider operating in the world, colliding protons and anti-protons at a center-of-mass energy of √s = 1.96 TeV. Its two interaction points are covered by the multi purpose particle detectors D0 and CDF. During the first data-taking period, known as Run I, the Tevatron operated at a center-of-mass energy of 1.8 TeV. This run period lasted from 1992 to 1996. During this period, the long-predicted top quark was discovered. From 1996 and 2001, the accelerator was upgraded to deliver higher instantaneous luminosities at its current center-of-mass energy. At the same time, the experiments were upgraded to take full advantage of the upgraded accelerator complex. The Tevatron is currently the only accelerator in the world with a sufficient energy to produce top quarks. Studying top quark production, decay and properties is an important part of the D0 and CDF physics programs. Because of its large mass, the top quark is a unique probe of the Standard Model, and an interesting environment to search for new physics. In this thesis, a measurement of the production cross-section of top quark pairs decaying to two muons is presented. In addition, a Monte Carlo study of the top quark spin correlation measurement was carried out. This thesis is laid out as follows: chapter two gives a short overview over the Standard Model of particle physics and the theoretical aspects of unpolarized and polarized top quark production and decay, chapter three describes the accelerator complex and the D0 experiment whose data is used in this analysis. The Reconstruction of events recorded with the D0 detector is explained in chapter four and the data and Monte Carlo samples used are presented in chapter five. Finally, the cross-section measurement is described in chapter six and the Monte Carlo study of top quark spin correlations in chapter seven.
Download or read book Study of the Top Quark Producttion Mechanism in 1 96 TeV Proton Antiproton Collisions written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis reports measurements of the production cross section of the top quark pairs and identification of the initial state of the subprocess, whether it is a gluon-gluon pair or a q$\bar{q}$ pair.
Download or read book Top Quark Pair Production in Proton Antiproton Collisions written by Freya Blekman and published by . This book was released on 2005 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Top Quark Pair Production written by Anna Christine Henrichs and published by Springer Science & Business Media. This book was released on 2013-10-04 with total page 231 pages. Available in PDF, EPUB and Kindle. Book excerpt: Before any kind of new physics discovery could be made at the LHC, a precise understanding and measurement of the Standard Model of particle physics' processes was necessary. The book provides an introduction to top quark production in the context of the Standard Model and presents two such precise measurements of the production of top quark pairs in proton-proton collisions at a center-of-mass energy of 7 TeV that were observed with the ATLAS Experiment at the LHC. The presented measurements focus on events with one charged lepton, missing transverse energy and jets. Using novel and advanced analysis techniques as well as a good understanding of the detector, they constitute the most precise measurements of the quantity at that time.
Download or read book Measurement of the Top Quark Pair Production Cross section in Dimuon Final States in Proton antiproton Collisions at 1 96 TeV written by Jens-Peter Konrath and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of the Single Top Quark Production Cross Section in 1 96 TeV Proton Antiproton Collisions written by and published by . This book was released on 2009 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: Top quarks are predominantly produced in pairs via the strong interaction in {bar p}p collisions at √s = 1.96 TeV . The top quark has a weak isospin 1/2, composing a weak isospin doublet with the bottom quark. This characteristic predicts not only top quark pair production via strong interaction but also single production together with a bottom quark via weak interaction. However, finding single top quark production is challenging since it is rarely produced ([sigma]{sub singletop} = 2.9 pb) against background processes with the same final state like W+jets and t{bar t}. A measurement of electroweak single top production probes the W-t-b vertex, which provides a direct determination of the Cabbibo-Kobayashi-Maskawa (CKM) matrix element.
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 Measurements of Top Quark Pair Production Cross Section in Proton Anti proton Collisions at S 1 2 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{bar p} → t{bar t}X production at √s = 1.96 TeV using 974.2 pb−1 of 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 [tau] 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 [tau] 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: [sigma](t{bar t}) = 6.9{sub -1.2}{sup +1.2}(stat){sub -0.7}{sup +0.8}(syst) ± 0.4 (lumi) pb. This indicates that our finding is consistent with the Standard Model prediction.
Download or read book Top Quark Pair Production Cross Section at Tevatron written by and published by . This book was released on 2009 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Measurement of the Spin Correlation in the Top Quark Pair Production Using the Dilepton Events in 1 96 TeV Proton Antiproton Collisions written by and published by . This book was released on 2012 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of Electroweak Single Top Quark Production in Proton antiproton Collisions at 1 96 TeV written by and published by . This book was released on 2008 with total page 235 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark is an extremely massive fundamental particle that is predominantly produced in pairs at particle collider experiments. The Standard Model of particle physics predicts that top quarks can also be produced singly by the electroweak force; however, this process is more difficult to detect because it occurs at a smaller rate and is more difficult to distinguish from background processes. The cross section of this process is related to the Cabbibo-Kobayashi-Maskawa matrix element.
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 InProton Anti proton Collisions at S 1 2 written by Tobias F. Golling and published by . This book was released on 2005 with total page 299 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Physics at the Large Hadron Collider written by Amitava Datta and published by Springer Science & Business Media. This book was released on 2010-05-30 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: In an epoch when particle physics is awaiting a major step forward, the Large Hydron Collider (LHC) at CERN, Geneva will soon be operational. It will collide a beam of high energy protons with another similar beam circulation in the same 27 km tunnel but in the opposite direction, resulting in the production of many elementary particles some never created in the laboratory before. It is widely expected that the LHC will discover the Higgs boson, the particle which supposedly lends masses to all other fundamental particles. In addition, the question as to whether there is some new law of physics at such high energy is likely to be answered through this experiment. The present volume contains a collection of articles written by international experts, both theoreticians and experimentalists, from India and abroad, which aims to acquaint a non-specialist with some basic issues related to the LHC. At the same time, it is expected to be a useful, rudimentary companion of introductory exposition and technical expertise alike, and it is hoped to become unique in its kind. The fact that there is substantial Indian involvement in the entire LHC endeavour, at all levels including fabrication, physics analysis procedures as well as theoretical studies, is also amply brought out in the collection.
Download or read book Studies of Top Quark Properties at the Tevatron written by and published by . This book was released on 2012 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: An overview of the recent measurements of the top quark properties in proton antiproton collisions at √s = 1.96 TeV is presented. These measurements are based on 5.4-8.7 fb−1 of data collected with the D0 and CDF experiments at the Fermilab Tevatron collider. The top quark mass and width measurements, studies of the spin correlation in top quark pair production, W boson helicity measurement, searches for anomalous top quark couplings and Lorentz invariance violation are discussed.
Download or read book Measurement of Top Quark Pair Production Cross Section in Proton Antiproton Collisions at square Root s written by Sohrab Hossain and published by . This book was released on 2009 with total page 278 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.
