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Download or read book A Direct Measurement of the Total Decay Width of the Top Quark written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Tomas Dado
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (115 download)
Download or read book Direct Measurement of the Top-quark Decay Width with the ATLAS Detector written by Tomas Dado and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark is the heaviest known elementary particle. Due to its large mass, the top quark decays before it forms bound states. This makes the top quark a unique particle in the Standard Model. Precise measurements of its properties could be used as tests of the consistency of the Standard Model and potential deviations could point to physics Beyond the Standard Model. This thesis deals with the direct measurement of the top-quark decay width using data collected in proton-proton collisions at centre-of-mass energies of 8 and 13 TeV with the ATLAS detector at the Large Hadron Collider. T...
Author : Philipp Stolte-Cord to Krax
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (11 download)
Download or read book Direct Top Quark Decay Width Measurement in the Tt̄ Lepton+Jets Channel at √s written by Philipp Stolte-Cord to Krax and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark t plays an essential role in the field of elementary particle physics - in particular due to its exceptional properties comprising a large mass, which approximately equals the mass of a tungsten atom, and an enormously short lifetime. This thesis is devoted to the study of a fundamental property of the top quark - its decay width. Its value is predicted by the established Standard Model of particle physics and deviations may hint at yet unknown physics beyond this model. A direct measurement of the decay width of the top quark is presented. The analysis is based on tt events i...
Author :
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ISBN 13 :
Total Pages : 7 pages
Book Rating : 4.:/5 (16 download)
Download or read book Measurements of the Top Quark Mass and Decay Width with the D0 Detector written by and published by . This book was released on 2011 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark discovery in 1995 at Fermilab is one of the major proofs of the standard model (SM). Due to its unique place in SM, the top quark is an important particle for testing the theory and probing for new physics. This article presents most recent measurements of top quark properties from the D0 detector. In particular, the measurement of the top quark mass, the top antitop mass difference and the top quark decay width. The discovery of the top quark in 1995 confirmed the existence of a third generation of quarks predicted in the standard model (SM). Being the heaviest elementary particle known, the top quark appears to become an important particle in our understanding of the standard model and physics beyond it. Because of its large mass the top quark has a very short lifetime, much shorter than the hadronization time. The predicted lifetime is only 3.3 · 10−25s. Top quark is the only quark whose properties can be studied in isolation. A Lorentz-invariant local Quantum Field Theory, the standard model is expected to conserve CP. Due to its unique properties, the top quark provides a perfect test of CPT invariance in the standard model. An ability to look at the quark before being hadronized allows to measure directly mass of the top quark and its antiquark. An observation of a mass difference between particle and antiparticle would indicate violation of CPT invariance. Top quark through its radiative loop correction to the W mass constrains the mass of the Higgs boson. A precise measurement of the top quark mass provides useful information to the search of Higgs boson by constraining its region of possible masses. Another interesting aspect is that the top quark's Yukawa coupling to the Higgs boson is very close to unity (0.996 ± 0.006). That implies it may play a special role in the electroweak symmetry breaking mechanism.
Author :
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ISBN 13 :
Total Pages : 81 pages
Book Rating : 4.:/5 (935 download)
Download or read book Measurement of the Decay Width of the Top Quark in the Semileptonic Channel written by and published by . This book was released on 2015 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Qichun Xu
Publisher :
ISBN 13 :
Total Pages : 288 pages
Book Rating : 4.3/5 (91 download)
Download or read book Direct Measurement of W Boson Decay Width at DO. written by Qichun Xu and published by . This book was released on 2001 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
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ISBN 13 :
Total Pages : 6 pages
Book Rating : 4.:/5 (873 download)
Download or read book Precision Measurements of the Top Quark Mass and Width with the D0 Detector written by and published by . This book was released on 2010 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the discovery of the top quark in 1995 at the Fermliab Tevatron Collider, top quark properties have been measured with ever higher precision. In this article, recent measurements of the top quark mass and its width using up to 3.6 fb−1 of D0 data are summarized. Different techniques and final states have been examined and no deviations within these measurements have been observed. In addition to the direct measurements, a measurement of the top quark mass from its production cross section and a measurement of the top-antitop quark mass difference are discussed. With a mass of 173.3 ± 1.1 GeV, the top quark is the heaviest of all known fundamental particles. Due to the high mass, its Yukawa coupling is close to unity suggesting that it may play a special role in electroweak symmetry breaking. Precise measurements of both, the W boson and the top quark mass, constrain the mass of the yet unobserved Higgs boson and allow to restrict certain extensions of the Standard Model. At the Tevatron collider with a center-of-mass energy of 1.96 TeV, 85% of the top quark pairs are produced in quark-antiquark annihilation; 15% originate from gluon fusion. Top quarks are predicted to decay almost exclusively to a W boson and a bottom quark. According to the number of hadronic W decays, top events are classified into all-jets, lepton+jets and dilepton events. The lepton+jets channel is characterized by four jets, one isolated, energetic charged lepton and missing transverse energy. With 30%, the branching fraction of the lepton+jets channel is about seven times larger than the one of the dilepton channel whereas the signal to background ratio is about three times smaller. The main background in this final state comes from W +jets events. Instrumental background arises from events in which a jet is misidentified as an electron and events with heavy hadrons that decay into leptons which pass the isolation requirements. The topology of the dilepton channel is described by two jets, two isolated, energetic charged leptons and significant missing transverse energy from the undetected neutrinos. The main background are Z + jets and diboson events (WW/WZ/ZZ+jets) as well as instrumental background as characterized above. At the D0 experiment, different techniques are used to measure the top quark mass. They are summarized in the following sections together with the first measurement of the top anti-top quark mass difference and the first precise determination of the top quark width.
Author :
Publisher :
ISBN 13 :
Total Pages : 147 pages
Book Rating : 4.:/5 (962 download)
Download or read book Measurements of the Top-quark Decay Width and Mass at CDF Using the Template Method written by and published by . This book was released on 2012 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements of the top quark decay width and mass are presented using the tt events produced in p p collisions at Fermilab's Tevatron collider and collected by the CDF II detector. A data sample corresponding to 4.3 fb-1 of integrated luminosity is used for the top quark width measurement. Two estimators, the reconstructed top quark mass and the mass of hadronically decaying W boson that comes from the top-quark decay are reconstructed for each event and compared with templates of different input top quark widths and deviations from nominal CDF jet energy scale ([Delta]JES) to perform a simultaneous fit for both parameters. [Delta]JES is used for the in situ calibration of the jet energy scale at CDF. By applying a Feldman-Cousins limit-setting approach, we establish an upper limit at 95% confidence level (CL) of [Gamma]top
Author : Thomas A. Schwarz
Publisher :
ISBN 13 :
Total Pages : 110 pages
Book Rating : 4.:/5 (316 download)
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.
Author :
Publisher :
ISBN 13 :
Total Pages : 193 pages
Book Rating : 4.:/5 (873 download)
Download or read book Measurement of the Top Quark Pair Production Cross Section in Proton-antiproton Collisions at a Center of Mass Energy of 1.96 TeV, Hadronic Top Decays with the D0 Detector written by and published by . This book was released on 2009 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: Of the six quarks in the standard model the top quark is by far the heaviest: 35 times more massive than its partner the bottom quark and more than 130 times heavier than the average of the other five quarks. Its correspondingly small decay width means it tends to decay before forming a bound state. Of all quarks, therefore, the top is the least affected by quark confinement, behaving almost as a free quark. Its large mass also makes the top quark a key player in the realm of the postulated Higgs boson, whose coupling strengths to particles are proportional to their masses. Precision measurements of particle masses for e.g. the top quark and the W boson can hereby provide indirect constraints on the Higgs boson mass. Since in the standard model top quarks couple almost exclusively to bottom quarks (t 2!Wb), top quark decays provide a window on the standard model through the direct measurement of the Cabibbo-Kobayashi-Maskawa quark mixing matrix element V{sub tb}. In the same way any lack of top quark decays into W bosons could imply the existence of decay channels beyond the standard model, for example charged Higgs bosons as expected in two-doublet Higgs models: t 2!Hb. Within the standard model top quark decays can be classified by the (lepton or quark) W boson decay products. Depending on the decay of each of the W bosons, t{bar t} pair decays can involve either no leptons at all, or one or two isolated leptons from direct W 2!e{bar {nu}}{sub e} and W 2![mu]{bar {nu}}{sub {mu}} decays. Cascade decays like b 2!Wc 2!e{bar {nu}}{sub e}c can lead to additional non-isolated leptons. The fully hadronic decay channel, in which both Ws decay into a quark-antiquark pair, has the largest branching fraction of all t{bar t} decay channels and is the only kinematically complete (i.e. neutrino-less) channel. It lacks, however, the clear isolated lepton signature and is therefore hard to distinguish from the multi-jet QCD background. It is important to measure the cross section (or branching fraction) in each channel independently to fully verify the standard model. Top quark pair production proceeds through the strong interaction, placing the scene for top quark physics at hadron colliders. This adds an additional challenge: the huge background from multi-jet QCD processes. At the Tevatron, for example, t{bar t} production is completely hidden in light q{bar q} pair production. The light (i.e. not bottom or top) quark pair production cross section is six orders of magnitude larger than that for t{bar t} production. Even including the full signature of hadronic t{bar t} decays, two b-jets and four additional jets, the QCD cross section for processes with similar signature is more than five times larger than for t{bar t} production. The presence of isolated leptons in the (semi)leptonic t{bar t} decay channels provides a clear characteristic to distinguish the t{bar t} signal from QCD background but introduces a multitude of W- and Z-related backgrounds.
Author :
Publisher :
ISBN 13 :
Total Pages : 7 pages
Book Rating : 4.:/5 (727 download)
Download or read book Measurement of the Top Quark Mass at written by and published by . This book was released on 2010 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The most recent measurements of the mass of the quark top at D0 are reviewed. The analysis methods include the direct measurement by Matrix Element and Weighting method and the indirect measurement from t{bar t} production cross section. They have been applied on different experimental signatures, all including at least one electron or muon. Measurements include from 1 to 3.6 fb−1 of D0 data. The most recent combination of mass measurements from D0 and from CDF are also quoted.
Author : Tom Paul Davids
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (137 download)
Download or read book A Maximum Likelihood Measurement Method for the Top Quark Decay Width written by Tom Paul Davids and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Jian Tang
Publisher :
ISBN 13 : 9781267836472
Total Pages : 148 pages
Book Rating : 4.8/5 (364 download)
Download or read book Measurements of the Top-quark Decay Width and Mass at CDF Using the Template Method written by Jian Tang and published by . This book was released on 2012 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements of the top quark decay width and mass are presented using the tt events produced in p p collisions at Fermilab's Tevatron collider and collected by the CDF II detector.
Author :
Publisher :
ISBN 13 :
Total Pages : 7 pages
Book Rating : 4.:/5 (873 download)
Download or read book Determination of the Width of the Top Quark written by and published by . This book was released on 2010 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Manfred Böhm
Publisher : Springer Science & Business Media
ISBN 13 : 3322801608
Total Pages : 796 pages
Book Rating : 4.3/5 (228 download)
Download or read book Gauge Theories of the Strong and Electroweak Interaction written by Manfred Böhm and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 796 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook gives a comprehensive summary of the gauge theories of the fundamental interactions. The authors stress the intimate connection between the basic experimental facts and the formulation of gauge theories of the strong and electroweak interaction. The concepts and technical tools of quantum field theory are presented. They are used to derive precision results of quantum chromodynamics and the standard model of the electroweak interaction of experiments in elementary particle physics. The book includes the latest experimental results and presents the actual status of the theory.
Author :
Publisher :
ISBN 13 :
Total Pages : 125 pages
Book Rating : 4.:/5 (16 download)
Download or read book Measurement of the Front Back Asymmetry in Top-antitop Quark Pairs Produced in P$\bar{p}$ Collisions at Center of Mass Energy {u221A}s written by and published by . This book was released on 2006 with total page 125 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$ar{p}$ collisions at 1.8 TeV at the Fermilab Tevatron. The mass of the top quark was measured to be 176 ± 13 GeV/c2 and the cross section 6.8$+3.6top{-2.4}$ pb. It is the Q = 2/3, T3 = +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$ar{p}$ collisions at the Tevatron. Top quark production at the Tevatron is almost exclusively by quark-antiquark annihilation, q$ar{q}$ → t$ar{t}$ (85%), and gluon fusion, gg → t$ar{t}$ (15%), mediated by the strong force. The theoretical cross-section for this process is ?t$ar{t}$ = 6.7 ± 0.8 pb for mt = 175 GeV/c2. Top quarks can also be produced at the Tevatron via q$ar{b}$' → tb and qg → q'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 → Wb). The total decay width t → Wb is ? = 1.50 GeV. This corresponds to an incredibly short lifetime of 0.5 x 10-24 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.
Author : Troy William Vine
Publisher :
ISBN 13 :
Total Pages : 372 pages
Book Rating : 4.:/5 (926 download)
Download or read book A direct measurement of the W decay width written by Troy William Vine and published by . This book was released on 2008 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt:
