Download or read book Measurement of the Top Quark Mass by Application of the Dalitz Goldstein Method to Dilepton Events written by Kristo Michael Karr and published by . This book was released on 1999 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents a measurement of the top quark mass by application of the Dalitz-Goldstein method to dilepton tt ̄ events. The events were produced by the Tevatron Collider at Fermi National Accelerator Laboratory (Fermilab) via pp ̄ collisions with s = 1.8 TeV. The dilepton event sample was extracted from 109 pb --1 of data collected by the Collider Detector at Fermilab (CDF) from August 1992 to July 1995. The sample contains a total of 9 candidate events, 2.4 of which are expected from background. Included in the dilepton final state are two neutrinos, which elude detection. This analysis constrains the problem by assuming an initial value for the top quark mass and solving for the neutrino momenta via a geometrical construction developed by D. H. Dalitz and G. Goldstein. The top quark mass is sampled over a wide range of possible values and the most likely mass consistent with the data is chosen via a likelihood function. An important distinguishing feature of this mass fitting technique is its lack of dependence on missing transverse energy, a kinematic variable that is poorly measured by experiment. This analysis determines the top quark mass to be Mtop = 157.1 +/- 10.9(stat.) +/- 4.33.7 (syst.) GeV/c2.
Download or read book Measurement of the Top Quark Mass in the Dilepton Final State Using the Matrix Element Method written by Alexander Grohsjean and published by Springer Science & Business Media. This book was released on 2010-10-01 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main pacemakers of scienti?c research are curiosity, ingenuity, and a pinch of persistence. Equipped with these characteristics a young researcher will be s- cessful in pushing scienti?c discoveries. And there is still a lot to discover and to understand. In the course of understanding the origin and structure of matter it is now known that all matter is made up of six types of quarks. Each of these carry a different mass. But neither are the particular mass values understood nor is it known why elementary particles carry mass at all. One could perhaps accept some small generic mass value for every quark, but nature has decided differently. Two quarks are extremely light, three more have a somewhat typical mass value, but one quark is extremely massive. It is the top quark, the heaviest quark and even the heaviest elementary particle that we know, carrying a mass as large as the mass of three iron nuclei. Even though there exists no explanation of why different particle types carry certain masses, the internal consistency of the currently best theory—the standard model of particle physics—yields a relation between the masses of the top quark, the so-called W boson, and the yet unobserved Higgs particle. Therefore, when one assumes validity of the model, it is even possible to take precise measurements of the top quark mass to predict the mass of the Higgs (and potentially other yet unobserved) particles.
Download or read book Measurement of the Top Quark Mass in the Di lepton Channel Using the Dalitz Goldstein Method written by and published by . This book was released on 2010 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation describes a measurement of the mass of the top quark using a method developed by G. Goldstein and R.H. Dalitz. It is based on 2.0 fb−1 of data collected by the Collider Detector Facility at Fermi National Accelerator Laboratories. Di-lepton events were observed from colliding protons with anti-protons with √s = 1.96 TeV in the Tevatron Collider. A total of 145 candidate events were observed with 49 expected to be from background. These events include two neutrinos which elude detection. The method begins by assuming an initial top quark mass and solves for the neutrino momenta using a geometrical construction. The method samples over a range of likely top quark masses choosing the most consistent mass via a likelihood function. An important distinguishing feature of this method from others is its lack of dependence on the missing transverse energy, a quantity that is poorly measured by the experiment. This analysis determines the top quark mass to be M{sub top} = 172.3 ± 3.4(stat.) ± 2.0(syst.) GeV/c2 (M{sub top} = 170.5 ± 3.7(stat.) ± 1.8(syst.) GeV/c2 with b-tagging).
Download or read book On Measuring the Top Quark Mass Using the Dilepton Decay Modes written by and published by . This book was released on 1996 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: We demonstrate a new likelihood method for extracting the top quark mass from events of the type {ital t}{ital {anti t}} --> {ital b}W({ital lepton+{nu}}){ital {anti b}}W−({ital lepton+{nu}}). This method estimates the top quark mass correctly from an ensemble of dilepton events. The method proposed by Dalitz and Goldstein is shown to result in a systematic underestimation of the top quark mass. Effects due to the spin correlations between the top and anti-top quarks are shown to be unimportant in estimating the mass of the top quark.
Download or read book The Evidence for the Top Quark written by Kent W. Staley and published by Cambridge University Press. This book was released on 2004-04-05 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Evidence for the Top Quark offers both a historical and philosophical perspective on an important recent discovery in particle physics: the first evidence for the elementary particle known as the top quark. Drawing on published reports, oral histories, and internal documents from the large collaboration that performed the experiment, Kent Staley explores in detail the controversies and politics that surrounded this major scientific result.At the same time the book seeks to defend an objective theory of scientific evidence based on error probabilities.
Download or read book Top Quark Mass Measurement from Dilepton Events at CDF II with the Matrix element Method written by and published by . This book was released on 2006 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of the Top Quark Mass in the Dilepton Final State Using the Matrix Element Method written by and published by . This book was released on 2008 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark, discovered in 1995 by the CDF and D0 experiments at the Fermilab Tevatron Collider, is the heaviest known fundamental particle. The precise knowledge of its mass yields important constraints on the mass of the yet-unobserved Higgs boson and allows to probe for physics beyond the Standard Model. The first measurement of the top quark mass in the dilepton channel with the Matrix Element method at the D0 experiment is presented. After a short description of the experimental environment and the reconstruction chain from hits in the detector to physical objects, a detailed review of the Matrix Element method is given. The Matrix Element method is based on the likelihood to observe a given event under the assumption of the quantity to be measured, e.g. the mass of the top quark. The method has undergone significant modifications and improvements compared to previous measurements in the lepton+jets channel: the two undetected neutrinos require a new reconstruction scheme for the four-momenta of the final state particles, the small event sample demands the modeling of additional jets in the signal likelihood, and a new likelihood is designed to account for the main source of background containing tauonic Z decay. The Matrix Element method is validated on Monte Carlo simulated events at the generator level. For the measurement, calibration curves are derived from events that are run through the full D0 detector simulation. The analysis makes use of the Run II data set recorded between April 2002 and May 2008 corresponding to an integrated luminosity of 2.8 fb−1. A total of 107 t{bar t} candidate events with one electron and one muon in the final state are selected. Applying the Matrix Element method to this data set, the top quark mass is measured to be m{sub top}{sup Run IIa} = 170.6 ± 6.1(stat.){sub -1.5}{sup +2.1}(syst.)GeV; m{sub top}{sup Run IIb} = 174.1 ± 4.4(stat.){sub -1.8}{sup +2.5}(syst.)GeV; m{sub top}{sup comb} = 172.9 ± 3.6(stat.) ± 2.3(syst.)GeV. Systematic uncertainties are discussed, and the results are interpreted within the Standard Model of particle physics. As the main systematic uncertainty on the top quark mass comes from the knowledge of the absolute jet energy scale, studies for a simultaneous measurement of the top quark mass and the b jet energy scale are presented. The prospects that such a simultaneous determination offer for future measurements of the top quark mass are outlined.
Download or read book Anomaly Collider Physics And The Quest For New Phenomena At Fermilab written by Tommaso Dorigo and published by World Scientific. This book was released on 2016-09-26 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: 'Dorigo provides an engaging and insightful perspective on the pursuit of physics discoveries at CDF … Dorigo’s book is thus almost certainly going to be an important source for anyone interested in the history of CDF … It is a personal yet highly informative story of discovery and almost-discovery from the perspective of someone who saw the events firsthand.'Physics TodayFrom the mid-1980s, an international collaboration of 600 physicists embarked on the investigation of subnuclear physics at the high-energy frontier. As well as discovering the top quark, the heaviest elementary particle ever observed, the physicists analyzed their data to seek signals of new physics which could revolutionize our understanding of nature.Anomaly! tells the story of that quest, and focuses specifically on the finding of several unexplained effects which were unearthed in the process. These anomalies proved highly controversial within the large team: to some collaborators they called for immediate publication, while to others their divulgation threatened to jeopardize the reputation of the experiment.Written in a confidential, narrative style, this book looks at the sociology of a large scientific collaboration, providing insight in the relationships between top physicists at the turn of the millennium. The stories offer an insider's view of the life cycle of the 'failed' discoveries that unavoidably accompany even the greatest endeavors in modern particle physics.
Download or read book Measurement of the Top Quark Mass Using Template Methods on Dilepton Events in P Anti p Collisions at S 1 2 written by and published by . This book was released on 2006 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors describe a measurement of the top quark mass from events produced in p{bar p} collisions at a center-of-mass energy of 1.96 TeV, using the Collider Detector at Fermilab. They identify t{bar t} candidates where both W bosons from the top quarks decay into leptons (e[nu], [mu][nu], or [tau][nu]) from a data sample of 360 pb−1. The top quark mass is reconstructed in each event separately by three different methods, which draw upon simulated distributions of the neutrino pseudorapidity, t{bar t} longitudinal momentum, or neutrino azimuthal angle in order to extract probability distributions for the top quark mass. For each method, representative mass distributions, or templates, are constructed from simulated samples of signal and background events, and parameterized to form continuous probability density functions. A likelihood fit incorporating these parameterized templates is then performed on the data sample masses in order to derive a final top quark mass. Combining the three template methods, taking into account correlations in their statistical and systematic uncertainties, results in a top quark mass measurement of 170.1 ± 6.0(stat.) ± 4.1(syst.) GeV/c2.
Download or read book Measurement of the Top Quark Mass Using Template Methods on Dilepton Events in P Anti p Collisions at S written by and published by . This book was released on 2006 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors describe a measurement of the top quark mass from events produced in p{bar p} collisions at a center-of-mass energy of 1.96 TeV, using the Collider Detector at Fermilab. They identify t{bar t} candidates where both W bosons from the top quarks decay into leptons (e?,??, or??) from a data sample of 360 pb−1. The top quark mass is reconstructed in each event separately by three different methods, which draw upon simulated distributions of the neutrino pseudorapidity, t{bar t} longitudinal momentum, or neutrino azimuthal angle in order to extract probability distributions for the top quark mass. For each method, representative mass distributions, or templates, are constructed from simulated samples of signal and background events, and parameterized to form continuous probability density functions. A likelihood fit incorporating these parameterized templates is then performed on the data sample masses in order to derive a final top quark mass. Combining the three template methods, taking into account correlations in their statistical and systematic uncertainties, results in a top quark mass measurement of 170.1 ± 6.0(stat.) ± 4.1(syst.) GeV/c2.
Download or read book 96 QCD and High Energy Hadronic Interactions written by J. Thanh Van Tran and published by Atlantica Séguier Frontières. This book was released on 1996 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics in Collision 19 written by M. Campbell and published by World Scientific. This book was released on 2000 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt: The XIX Physics in Collision conference reviewed experimental results in electroweak, quantum chromodynamics, neutrino, bottom and rare kaon physics, and updated recent developments in the area of gamma ray bursts as well as the issue of the cosmological constant and dark matter.The conference opened with reports on electroweak physics. A decade of precision experiments in laboratories around the world failed to uncover any significant deviations from standard model predictions. Precise W boson and top quark mass measurements suggest a low mass Higgs boson in the standard model, possibly within the reach of the LEP II and the upgraded Tevatron colliders. These presentations were followed by a summary of the latest results on searches for Higgs and supersymmetry.There were three reports on neutrino physics: atmospheric, solar and reactor/accelerator based neutrino experiments and results. Impressive Super-K results strongly suggest ????? oscillation, a scenario confirmed by less precise Soudan2 and MACRO data.The latest results on strange and heavy quark physics were summarized. High statistics from CLEO, LEP I and Tevatron have enabled experimenters to study many rare charm and bottom quark decays for the first time. Among many other interesting results presented, the first measurements of sin 2? by CDF and î?/î by KTeV provide a preview of expected developments in the near future.
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.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1999 with total page 856 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the International Europhysics Conference on High Energy Physics written by John Carr and published by Atlantica Séguier Frontières. This book was released on 1994 with total page 1044 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics In Collision Xix Procs written by Myron Campbell and published by World Scientific. This book was released on 2000-07-27 with total page 389 pages. Available in PDF, EPUB and Kindle. Book excerpt: The XIX Physics in Collision conference reviewed experimental results in electroweak, quantum chromodynamics, neutrino, bottom and rare kaon physics, and updated recent developments in the area of gamma ray bursts as well as the issue of the cosmological constant and dark matter.The conference opened with reports on electroweak physics. A decade of precision experiments in laboratories around the world failed to uncover any significant deviations from standard model predictions. Precise W boson and top quark mass measurements suggest a low mass Higgs boson in the standard model, possibly within the reach of the LEP II and the upgraded Tevatron colliders. These presentations were followed by a summary of the latest results on searches for Higgs and supersymmetry.There were three reports on neutrino physics: atmospheric, solar and reactor/accelerator based neutrino experiments and results. Impressive Super-K results strongly suggest νμ→νς oscillation, a scenario confirmed by less precise Soudan2 and MACRO data.The latest results on strange and heavy quark physics were summarized. High statistics from CLEO, LEP I and Tevatron have enabled experimenters to study many rare charm and bottom quark decays for the first time. Among many other interesting results presented, the first measurements of sin 2β by CDF and ε′/ε by KTeV provide a preview of expected developments in the near future.
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.
