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Top Decays And Mass With Cdf
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Download or read book Top Decays and Mass with CDF. written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors report preliminary results on top quark decays and measurements of the top mass recently obtained by the CDF collaboration, using a data sample of about 110 pb[sup[minus]1] collected at the Tevatron collider. Upper limits for non Standard model top decays into W+ q (non b quark), Z+ q and[gamma]+ q are given. Top mass measurements are obtained in three topologies for t[anti t] production and decay into W b: lepton+[ge] 4 jets, di-lepton and all hadronic final states. The most precise measurement is obtained in the lepton+[ge] 4 jets topology using 34 events which have at least one jet tagged by the SVX or SLT b-tagging algorithms and a good constrained kinematics fit.
Book Synopsis Measurements of the Top-quark Decay Width and Mass at CDF Using the Template Method by :
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
Book Synopsis Measurements of the Top-quark Decay Width and Mass at CDF Using the Template Method by : Jian Tang
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.
Book Synopsis Top Quark Physics at Hadron Colliders by : Arnulf Quadt
Download or read book Top Quark Physics at Hadron Colliders written by Arnulf Quadt and published by Springer Science & Business Media. This book was released on 2007-08-16 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: This will be a required acquisition text for academic libraries. More than ten years after its discovery, still relatively little is known about the top quark, the heaviest known elementary particle. This extensive survey summarizes and reviews top-quark physics based on the precision measurements at the Fermilab Tevatron Collider, as well as examining in detail the sensitivity of these experiments to new physics. Finally, the author provides an overview of top quark physics at the Large Hadron Collider.
Download or read book CDF Top Physics written by and published by . This book was released on 1996 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors present the latest results about top physics obtained by the CDF experiment at the Fermilab Tevatron collider. The data sample used for these analysis (about 110 pb−1) represents almost the entire statistics collected by CDF during four years (1992--95) of data taking. This large data size has allowed detailed studies of top production and decay properties. The results discussed here include the determination of the top quark mass, the measurement of the production cross section, the study of the kinematics of the top events and a look at top decays.
Book Synopsis Top Decay Physics at CDF and Measurement of the CKM Element V{sub Tb} by :
Download or read book Top Decay Physics at CDF and Measurement of the CKM Element V{sub Tb} written by and published by . This book was released on 1995 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: Now that the top quark's existence has been firmly established by the CDF and D0 experiments{sup 1,2)}, we begin to measure its properties. Branching fractions are of particular interest in the case of the t quark, since they probe the couplings of the top quark to gauge bosons and other quarks, and because ''the top quark is the only quark with reasonable mass''3}. Because the top quark is the only quark with mass comparable to the electroweak scale, its decays, particularly non-standard decays, might shed some light on what makes the top quark different from lighter quarks, and the role it plays in electroweak symmetry breaking. This paper describes some recent measurements on the decay of the top quark using the CDF detector, a general purpose detector designed to study p{bar p} collisions at (square root)s=1.8 TeV; it has been described in detail elsewhere{sup 4,1)}. The analyses presented use 100-110 pb-1 of data collected between 1992 and 1995 at the Fermilab TeVatron.
Book Synopsis A Measurement of the Top Quark Mass in the Dilepton Decay Channel at CDF II. by : Bodhitha Anjalike Jayatilaka
Download or read book A Measurement of the Top Quark Mass in the Dilepton Decay Channel at CDF II. written by Bodhitha Anjalike Jayatilaka and published by . This book was released on 2006 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis B Decays (Revised 2nd Edition) by : Sheldon Stone
Download or read book B Decays (Revised 2nd Edition) written by Sheldon Stone and published by World Scientific. This book was released on 1994-08-01 with total page 673 pages. Available in PDF, EPUB and Kindle. Book excerpt: This 2nd edition is an extensive update of 'B Decays”. The revisions are necessary because of the extensive amount of new data and new theoretical ideas. This book reviews what is known about b-quark decays and also looks at what can be learned in the future.The importance of this research area is increasing, as evidenced by the approval of the luminosity upgrade for CESR and the asymmetric B factories at SLAC and KEK, and the possibility of experiments at hadron colliders.The key experimental observations made thus far, measurement of the lifetimes of the different B species, B0-B0 mixing, the discovery of “Penguin” mediated decays, and the extraction of the CKM matrix elements Vub and Vcb from semileptonic decays, as well as more mundane results, are described in great detail by the experimentalists who have been closely involved with making the measurements. Theoretical progress in understanding b-quark decays using HQET and lattice gauge techniques are described by theorists who have developed and used these techniques.Synthesizing the experimental and theoretical information, several articles discuss the implications for the “Standard Model” and how further tests can be done using measurements of CP violation in the B system.
Book Synopsis Measurement of the Top Quark Mass Simultaneously in Dilepton and Lepton + Jets Decay Channels by :
Download or read book Measurement of the Top Quark Mass Simultaneously in Dilepton and Lepton + Jets Decay Channels written by and published by . This book was released on 2008 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors present the first measurement of the top quark mass using simultaneously data from two decay channels. They use a data sample of (square root)s = 1.96 TeV collisions with integrated luminosity of 1.9 fb−1 collected by the CDF II detector. They select dilepton and lepton + jets channel decays of t{bar t} pairs and reconstruct two observables in each topology. They use non-parametric techniques to derive probability density functions from simulated signal and background samples. The observables are the reconstructed top quark mass and the scalar sum of transverse energy of the event in the dilepton topology and the reconstructed top quark mass and the invariant mass of jets from the W boson decay in lepton + jets channel. They perform a simultaneous fit for the top quark mass and the jet energy scale which is constrained in situ by the hadronic W boson resonance from the lepton + jets channel. Using 144 dilepton candidate events and 332 lepton + jets candidate events they measure: M{sub top} = 171.9 ± 1.7 (stat. + JES) ± 1.1 (other sys.) GeV/c2 = 171.9 ± 2.0 GeV/c2. The measurement features a robust treatment of the systematic uncertainties, correlated between the two channels and develops techniques for a future top quark mass measurement simultaneously in all decay channels. Measurements of the W boson mass and the top quark mass provide a constraint on the mass of the yet unobserved Higgs boson. The Higgs boson mass implied by measurement presented here is higher than Higgs boson mass implied by previously published, most precise CDF measurements of the top quark mass in lepton + jets and dilepton channels separately.
Book Synopsis Measurements and Searches with Top Quarks by :
Download or read book Measurements and Searches with Top Quarks written by and published by . This book was released on 2008 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 1995 the last missing member of the known families of quarks, the top quark, was discovered by the CDF and D0 experiments at the Tevatron, a proton-antiproton collider at Fermilab near Chicago. Until today, the Tevatron is the only place where top quarks can be produced. The determination of top quark production and properties is crucial to understand the Standard Model of particle physics and beyond. The most striking property of the top quark is its mass--of the order of the mass of a gold atom and close to the electroweak scale--making the top quark not only interesting in itself but also as a window to new physics. Due to the high mass, much higher than of any other known fermion, it is expected that the top quark plays an important role in electroweak symmetry breaking, which is the most prominent candidate to explain the mass of particles. In the Standard Model, electroweak symmetry breaking is induced by one Higgs field, producing one additional physical particle, the Higgs boson. Although various searches have been performed, for example at the Large Electron Positron Collider (LEP), no evidence for the Higgs boson could yet be found in any experiment. At the Tevatron, multiple searches for the last missing particle of the Standard Model are ongoing with ever higher statistics and improved analysis techniques. The exclusion or verification of the Higgs boson can only be achieved by combining many techniques and many final states and production mechanisms. As part of this thesis, the search for Higgs bosons produced in association with a top quark pair (t{bar t}H) has been performed. This channel is especially interesting for the understanding of the coupling between Higgs and the top quark. Even though the Standard Model Higgs boson is an attractive candidate, there is no reason to believe that the electroweak symmetry breaking is induced by only one Higgs field. In many models more than one Higgs boson are expected to exist, opening even more channels to search for charged or neutral Higgs bosons. Depending on its mass, the charged Higgs boson is expected to decay either into top quarks or be the decay product of a top quark. For masses below the top quark mass, the top decay into a charged Higgs boson and a b quark can occur at a certain rate, additionally to the decays into W bosons and a b quark. The different decays of W and charged Higgs bosons can lead to deviations of the observed final number of events in certain final states with respect to the Standard Model expectation. A global search for charged Higgs bosons in top quark pair events is presented in this thesis, resulting in the most stringent limits to-date. Besides the decay of top quarks into charged Higgs or W bosons, new physics can also show up in the quark part of the decay. While in the Standard Model the top quark decays with a rate of about 100% into a W boson and a b quark, there are models where the top quark can decay into a W boson and a non-b quark. The ratio of branching fractions in which the top quark decays into a b quark over the branching fractions in which the top quark decays into all quarks is measured as part of this thesis, yielding the most precise measurement today. Furthermore, the Standard Model top quark pair production cross section is essential to be known precisely since the top quark pair production is the main background for t{bar t}H production and many other Higgs and beyond the Standard Model searches. However, not only the search or the test of the Standard Model itself make the precise measurement of the top quark pair production cross section interesting. As the cross section is calculated with high accuracy in perturbative QCD, a comparison of the measurement to the theory expectation yields the possibility to extract the top quark mass from the cross section measurement. Although many dedicated techniques exist to measure the top quark mass, the extraction from the cross section represents an important complementary measurement. The latter is briefly discussed in this thesis and compared to direct top mass measurements. The goal of this thesis is the improved understanding of the top quark sector and its use as a window to new physics. Techniques are extended and developed to measure the top quark pair production cross section simultaneously with the ratio of branching fractions, the t{bar t}H cross section or the rate with which top quarks decay into charged Higgs bosons. Some of the results are then taken to extract more information. The cross section measurement is used to extract the top quark mass, and the ratio of the top quark pair production cross sections in different final states, yielding a limit on non-Standard Model top quark decays.
Book Synopsis Measurement of the W Boson Helicity in Top-antitop Quark Events with the CDF II Experiment by : Thorsten Chwalek
Download or read book Measurement of the W Boson Helicity in Top-antitop Quark Events with the CDF II Experiment written by Thorsten Chwalek and published by . This book was released on 2006 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 1995 the top quark was discovered at the Tevatron proton-antiproton collider at Fermilab by the CDF and D0 collaborations [1, 2]. It is the most massive known elementary particle and its mass is currently measured with a precision of about 1.3% [3, 4]. However, the measurements of several other top quark properties are still statistically limited, so the question remains whether the Standard Model of elementary particle physics successfully predicts these properties. This thesis addresses one interesting aspect of top quark decay, the helicity of the produced W boson. Until the start of the Large Hadron Collider (LHC) at CERN, the Tevatron with a center-of-mass energy of {radical}s = 1.96 TeV is the only collider, where top quarks can be produced. In the Standard Model the top quark decays predominantly into a W boson and a b quark, with a branching ratio close to 100%. The V-A structure of the weak interaction of the Standard Model predicts that the W{sup +} bosons from the top quark decay t {yields} W{sup +}b are dominantly either longitudinally polarized or left handed, while right handed W bosons are heavily suppressed and even forbidden in the limit of a massless b quark. Under the assumption of a massless b quark, for a top quark mass of 173 GeV/c{sup 2} the Standard Model predicts the fraction F0 of longitudinally polarized W bosons to be 0.7 and 0.3 for the fraction F{_} of left handed W bosons, while the fraction F{sub +} of right handed W bosons is predicted to be zero. Since next-to-leading order corrections change these fractions only slightly, a significant deviation from the predicted value for F{sub 0} or a nonzero value for F{sub +} could indicate new physics. Left-right symmetric models [5], for example, lead to a significant right handed fraction of W bosons in top decays. Such a right handed component (V+A coupling) would lead to a smaller left handed fraction, while F{sub 0} would remain unchanged. Since the decay rate to longitudinal W bosons depends on the Yukawa coupling of the top quarks, the measurement of F{sub 0} is sensitive to the mechanism of electroweak symmetry breaking. Alternative models can lead to an altered F{sub 0} fraction. In this analysis the W helicity fractions are measured in a selected sample rich in t{bar B} events where one lepton, at least four jets, and missing transverse energy are required. All kinematic quantities describing the t{bar t} decay are determined. As a sensitive observable, we use the cosine of the decay angle {theta}*, which is defined as the angle between the momentum of the charged lepton in the W boson rest frame and the W boson momentum in the top quark rest frame. The data used in this analysis were taken with the Collider Detector at Fermilab (CDF II) in the years 2002-2006 and correspond to an integrated luminosity of about 955 pb{sup -1}. Previous CDF measurements of the W boson helicity fractions in top quark decays used either the square of the invariant mass of the charged lepton and the b quark jet, M{sub {ell}b}{sup 2}, or the lepton p{sub T} distribution as a discriminant. The D0 collaboration used a matrix-element method to extract a value of F{sub 0}; in a second analysis the reconstructed distribution of cos {theta}* was utilized to measure F{sub +}. CDF gives the latest value of F{sub 0} = 0.74{sub -0.34}{sup +0.22}, while D measured F{sub 0} = 0.56 {+-} 0.31. The CDF collaboration also gives the current upper limit of F{sub +}
Book Synopsis Combining the Top Quark Mass Results for Run 1 from CDF and D-Zero by :
Download or read book Combining the Top Quark Mass Results for Run 1 from CDF and D-Zero written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: CDF and D0 have published or submitted for publication eleven papers [1-11] that include direct experimental measurements of the top quark mass. Each experiment has found that the lepton+jets channel [1,5,6,9,10,11,12] gives the most precise result. However, CDF and D0 have also measured the top quark mass in other decay topologies. Both D0 [2,6] and CDF [3,4] have published additional results in the dilepton channels, while CDF [8] has published a result in the all-hadronic channel. Our aim in this note is to reduce the overall uncertainty on the top quark mass measurement by combining the most recent and final of these measurements [1,2,3,7,8]. This note combines the mass from the five separate measurements taking into account the statistical and systematic uncertainties as well as the correlations in the systematic uncertainties. The final Tevatron top mass based on Run 1 data is m{sub t} = 174.3 " 3.2(stat) " 4.0(syst) GeV/c2. Combining the statistical and systematic uncertainties, the top mass is m{sub t} = 174.3 " 5.1 GeV/c2.
Book Synopsis Top Quark Decay Kinematics in Fully Reconstructed Tt̄ Events in the E Or [mu] + EṮ + [greater Than Or Equal To] 4 Jet Decay Channel by : Eugene Hall Guillian
Download or read book Top Quark Decay Kinematics in Fully Reconstructed Tt̄ Events in the E Or [mu] + EṮ + [greater Than Or Equal To] 4 Jet Decay Channel written by Eugene Hall Guillian and published by . This book was released on 1999 with total page 852 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Top Quark Mass Measurement written by and published by . This book was released on 2008 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark is the heaviest elementary particle. Its mass is one of the fundamental parameters of the standard model of particle physics, and an important input to precision electroweak tests. This thesis describes three measurements of the top-quark mass in the dilepton decay channel. The dilepton events have two neutrinos in the final state; neutrinos are weakly interacting particles that cannot be detected with a multipurpose experiment. Therefore, the signal of dilepton events consists of a large amount of missing energy and momentum carried off by the neutrinos. The top-quark mass is reconstructed for each event by assuming an additional constraint from a top mass independent distribution. Template distributions are constructed from simulated samples of signal and background events, and parametrized to form continuous probability density functions. The final top-quark mass is derived using a likelihood fit to compare the reconstructed top mass distribution from data to the parametrized templates. One of the analyses uses a novel technique to add top mass information from the observed number of events by including a cross-section-constraint in the likelihood function. All measurements use data samples collected by the CDF II detector.
Book Synopsis CDF Measurement of the Top Quark Mass in the Lepton + Jets Channel Using the Multivariate Template Method by : John Freeman
Download or read book CDF Measurement of the Top Quark Mass in the Lepton + Jets Channel Using the Multivariate Template Method written by John Freeman and published by . This book was released on 2004 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors measure the mass of the top quark using 162 pb{sup -1} of data collected by the CDF experiment at FNAL in Run II. The decay chain t{bar t} {yields} bq{bar q}{bar b}lv is studied using a novel technique called the Multivariate Template Method (MTM). Using this technique they obtain a result of M{sub top} = 179.6{sub -6.3}{sup +6.4} {+-} 6.8 GeV/c{sup 2} for the top quark.
Book Synopsis Top Mass Measurement at CDF. by : Kostas Kordas
Download or read book Top Mass Measurement at CDF. written by Kostas Kordas and published by . This book was released on 2006 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: We report on recent measurements of the top quark mass using t{bar t} candidate events selected in {approx_equal} 320 pb{sup -1} of data from the ''Run II'' operation period of the Tevatron p{bar p} collider. More emphasis is given on the best single measurement to date (M{sub top} = 173.5{sub -3.8}{sup +3.9} GeV/c{sup 2}), provided by CDF using the ''lepton plus jets'' channel, where one W decays to a lepton-neutrino pair and the other into quarks (top quarks decay to Wb almost 100% of the time).
Book Synopsis Studies of Kinematic Distributions and Mass Reconstruction of CDF Top Candidate Events by :
Download or read book Studies of Kinematic Distributions and Mass Reconstruction of CDF Top Candidate Events written by and published by . This book was released on 1994 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present analyses of CDF top-candidate events which study the separation of signal from background using easily-defined kinematic variables, and which study invariant masses of three-body systems to fully reconstruct the top quark decay products.
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