Download or read book Evidence for Production of Single Top Quarks and First Direct Measurement of written by and published by . This book was released on 2006 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The D0 Collaboration presents first evidence for the production of single top quarks at the Fermilab Tevatron p{bar p} collider. Using a 0.9 fb−1 dataset, we apply a multivariate analysis to separate signal from background and measure [sigma](p{bar p} 2!tb + X, tqb + X) = 4.9 ± 1.4 pb. The probability to measure a cross section at this value or higher in the absence of signal is 0.035%, corresponding to a 3.4 standard deviation significance. We use the cross section measurement to directly determine the CKM matrix element that describes the W tb coupling and find 0.68>

Download or read book Discovery of Single Top Quark Production written by Dag Gillberg and published by Springer Science & Business Media. This book was released on 2011-01-22 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark is by far the heaviest known fundamental particle with a mass nearing that of a gold atom. Because of this strikingly high mass, the top quark has several unique properties and might play an important role in electroweak symmetry breaking—the mechanism that gives all elementary particles mass. Creating top quarks requires access to very high energy collisions, and at present only the Tevatron collider at Fermilab is capable of reaching these energies. Until now, top quarks have only been observed produced in pairs via the strong interaction. At hadron colliders, it should also be possible to produce single top quarks via the electroweak interaction. Studies of single top quark production provide opportunities to measure the top quark spin, how top quarks mix with other quarks, and to look for new physics beyond the standard model. Because of these interesting properties, scientists have been looking for single top quarks for more than 15 years. This thesis presents the first discovery of single top quark production. It documents one of the flagship measurements of the D0 experiment, a collaboration of more than 600 physicists from around the world. It describes first observation of a physical process known as “single top quark production”, which had been sought for more than 10 years before its eventual discovery in 2009. Further, his thesis describes, in detail, the innovative approach Dr. Gillberg took to this analysis. Through the use of Boosted Decision Trees, a machine-learning technique, he observed the tiny single top signal within an otherwise overwhelming background. This Doctoral Thesis has been accepted by Simon Fraser University, Burnaby, BC, Canada.

Download or read book Higher Order QCD Corrections to Single Top Quark Production written by Mohammad Assadsolimani and published by disserta Verlag. This book was released on 2014-08 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is known that the LHC has a considerable discovery potential because of its large centre-of-mass energy (vs =14 TeV) and the high design luminosity. In addition, the two experiments ATLAS and CMS perform precision measurements for numerous models in physics. The increasing experimental precision demands an even higher level of accuracy on the theoretical side. For a more precise prediction of outcomes, one has to consider the corrections obtained typically from Quantum Chromodynamics (QCD). The calculation of these corrections in the high energy regime is described by perturbation theory. In the present study, multi-loop calculations in QCD, including in particular two-loop corrections for single top quark production, are considered. There are several phenomenological motivations to study single top quark production: Firstly, the process is sensitive to the electroweak Wtb-vertex; moreover, non-standard couplings can hint at physics beyond the Standard Model. Secondly, the t-channel cross section measurement provides information on the b-quark Parton Distribution Functions (PDF). Finally, single top quark production enables us to directly measure the Cabibbo-Kobayashi-Maskawa(CKM) matrix element Vtb. The next-to-next-to-leading-order (NNLO) calculation of the single top quark production has many building blocks. In this study, two blocks will be presented: one-loop corrections squared and two-loop corrections interfered with Born. Initially, the one-loop squared contribution at NNLO for single top quark production will be calculated. Before we begin with the calculation of the two-loop corrections to single top quark production, we calculate the QCD form factors of heavy quarks at NNLO, along with the axial vector coupling as a first independent check. A comparison with the relevant literature suggests that this approach is in line with generally accepted procedure. This consistency check provides a proof of the validity of our setup. In the next step, the two-loop corrections to single top quark production will be calculated. After reducing all occurring tensor integrals to scalar integrals, we apply the integration by parts method (IBP) to find the master integrals. This step is a major challenge compared to all similar calculations because of the number of variables in the problem (two Mandelstam variables s and t, the dimension d and the mass of the top quark mt as well as the mass of the W boson mw). Finally, the calculation of the three kinds of topologies – vertex corrections, double boxes and non-planar double boxes – in the two-loop contribution at NNLO calculation will be presented.

Download or read book Perspectives on LHC Physics written by Aaron Pierce and published by World Scientific. This book was released on 2008 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Large Hadron Collider (LHC), located at CERN, Geneva, Switzerland, is the world's largest and highest energy and highest intensity particle accelerator. This book provides an overview on the techniques that will be crucial for finding new physics at the LHC, as well as perspectives on the importance and implications of the discoveries. Among the contributors to this book are leaders and visionaries in the field of particle physics beyond the Standard Model, including two Nobel Laureates (Steven Weinberg and Frank Wilczek), and presumably some future Nobel Laureates, plus top younger theorists and experimenters.

Download or read book Single Top Quark Production at the Tevatron written by and published by . This book was released on 2008 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Tevatron experiments D0 and CDF have found evidence for single top quark production, based on datasets between 0.9 fb−1 and 2.2 fb−1. Several different multivariate techniques are used to extract the single top quark signal out of the large backgrounds. The cross section measurements are also used to provide the first direct measurement of the CKM matrix element.

Download or read book Shifting Standards written by Allan Franklin and published by University of Pittsburgh Press. This book was released on 2018-11-24 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: In Shifting Standards, Allan Franklin provides an overview of notable experiments in particle physics. Using papers published in Physical Review, the journal of the American Physical Society, as his basis, Franklin details the experiments themselves, their data collection, the events witnessed, and the interpretation of results. From these papers, he distills the dramatic changes to particle physics experimentation from 1894 through 2009. Franklin develops a framework for his analysis, viewing each example according to exclusion and selection of data; possible experimenter bias; details of the experimental apparatus; size of the data set, apparatus, and number of authors; rates of data taking along with analysis and reduction; distinction between ideal and actual experiments; historical accounts of previous experiments; and personal comments and style. From Millikan's tabletop oil-drop experiment to the Compact Muon Solenoid apparatus measuring approximately 4,000 cubic meters (not including accelerators) and employing over 2,000 authors, Franklin's study follows the decade-by-decade evolution of scale and standards in particle physics experimentation. As he shows, where once there were only one or two collaborators, now it literally takes a village. Similar changes are seen in data collection: in 1909 Millikan's data set took 175 oil drops, of which he used 23 to determine the value of e, the charge of the electron; in contrast, the 1988-1992 E791 experiment using the Collider Detector at Fermilab, investigating the hadroproduction of charm quarks, recorded 20 billion events. As we also see, data collection took a quantum leap in the 1950s with the use of computers. Events are now recorded at rates as of a few hundred per second, and analysis rates have progressed similarly. Employing his epistemology of experimentation, Franklin deconstructs each example to view the arguments offered and the correctness of the results. Overall, he finds that despite the metamorphosis of the process, the role of experimentation has remained remarkably consistent through the years: to test theories and provide factual basis for scientific knowledge, to encourage new theories, and to reveal new phenomenon.

Download or read book Measurement of Single Top Quark Production in the Tau jets Channel Using Boosted Decision Trees at D0 written by Zhiyi Liu and published by . This book was released on 2009 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark is the heaviest known matter particle and plays an important role in the Standard Model of particle physics. At hadron colliders, it is possible to produce single top quarks via the weak interaction. This allows a direct measurement of the CKM matrix element Vtb and serves as a window to new physics. The first direct measurement of single top quark production with a tau lepton in the final state (the tau+jets channel) is presented in this thesis. The measurement uses 4.8 fb1 of Tevatron Run II data in p\bar{p} collisions at \sqrt{s}=1.96 TeV acquired by the D0 experiment. After selecting a data sample and building a background model, the data and background model are in good agreement. A multivariate technique, boosted decision trees, is employed in discriminating the small single top quark signal from a large background. The expected sensitivity of the tau+jets channel in the Standard Model is 1.8 standard deviations. Using a Bayesian statistical approach, an upper limit on the cross section of single top quark production in the tau+jets channel is measured as 7.3 pb at 95% confidence level, and the cross section is measured as 3.4+2.0−1.8 pb. The result of the single top quark production in the tau+jets channel is also combined with those in the electron+jets and muon+jets channels. The expected sensitivity of the electron, muon and tau combined analysis is 4.7 standard deviations, to be compared to 4.5 standard deviations in electron and muon alone. The measured cross section in the three combined final states is sigma(p\bar{p}->tb+X,tqb+X) = 3.84+0.89−0.83 pb. A lower limit on Vth is also measured in the three combined final states to be alrger than 0.85 at 95% confidence level. These results are consistent with Standard Model expectations.

Download or read book Artificial Intelligence For High Energy Physics written by Paolo Calafiura and published by World Scientific. This book was released on 2022-01-05 with total page 829 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Higgs boson discovery at the Large Hadron Collider in 2012 relied on boosted decision trees. Since then, high energy physics (HEP) has applied modern machine learning (ML) techniques to all stages of the data analysis pipeline, from raw data processing to statistical analysis. The unique requirements of HEP data analysis, the availability of high-quality simulators, the complexity of the data structures (which rarely are image-like), the control of uncertainties expected from scientific measurements, and the exabyte-scale datasets require the development of HEP-specific ML techniques. While these developments proceed at full speed along many paths, the nineteen reviews in this book offer a self-contained, pedagogical introduction to ML models' real-life applications in HEP, written by some of the foremost experts in their area.

Download or read book Graduate Programs in the Physical Sciences Mathematics Agricultural Sciences the Environment Natural Resources 2011 Grad 4 written by Peterson's and published by Peterson's. This book was released on 2011-05-01 with total page 2669 pages. Available in PDF, EPUB and Kindle. Book excerpt: Peterson's Graduate Programs in the Physical Sciences, Mathematics, Agricultural Sciences, the Environment & Natural Resources contains a wealth of information on colleges and universities that offer graduate work in these exciting fields. The institutions listed include those in the United States and Canada, as well international institutions that are accredited by U.S. accrediting bodies. Up-to-date information, collected through Peterson's Annual Survey of Graduate and Professional Institutions, provides valuable information on degree offerings, professional accreditation, jointly offered degrees, part-time and evening/weekend programs, postbaccalaureate distance degrees, faculty, students, degree requirements, entrance requirements, expenses, financial support, faculty research, and unit head and application contact information. Readers will find helpful links to in-depth descriptions that offer additional detailed information about a specific program or department, faculty members and their research, and much more. In addition, there are valuable articles on financial assistance, the graduate admissions process, advice for international and minority students, and facts about accreditation, with a current list of accrediting agencies.

Download or read book Fundamental Interactions Proceedings Of The 22nd Lake Louise Winter Institute written by Alan Astbury and published by World Scientific. This book was released on 2007-12-28 with total page 487 pages. Available in PDF, EPUB and Kindle. Book excerpt: This proceedings volume contains the latest results from the field of particle physics. The contributions cover the current status of all the Large Hadron Collider (LHC) experiments, the implications of the LHC for cosmology, and the search for dark matter and nuclear astrophysics. It also includes work on the current status of the future International Linear Collider (ILC).

Download or read book Phenomenology of Particle Physics written by André Rubbia and published by Cambridge University Press. This book was released on 2022-05-12 with total page 1111 pages. Available in PDF, EPUB and Kindle. Book excerpt: Addresses the theoretical and experimental phenomenology of particle physics for two-semester Masters and graduate courses.

Download or read book Fundamental Interactions written by Alan Astbury and published by World Scientific. This book was released on 2008 with total page 487 pages. Available in PDF, EPUB and Kindle. Book excerpt: This proceedings volume contains the latest results from the field of particle physics. The contributions cover the current status of all the Large Hadron Collider (LHC) experiments, the implications of the LHC for cosmology, and the search for dark matter and nuclear astrophysics. It also includes work on the current status of the future International Linear Collider (ILC).

Download or read book Evidence for Production of Single Top Quarks written by and published by . This book was released on 2008 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present first evidence for the production of single top quarks in the D0 detector at the Fermilab Tevatron p{bar p} collider. The standard model predicts that the electroweak interaction can produce a top quark together with an antibottom quark or light quark, without the antiparticle top quark partner that is always produced from strong coupling processes. Top quarks were first observed in pair production in 1995, and since then, single top quark production has been searched for in ever larger datasets. In this analysis, we select events from a 0.9 fb−1 dataset that have an electron or muon and missing transverse energy from the decay of a W boson from the top quark decay, and two, three, or four jets, with one or two of the jets identified as originating from a b hadron decay. The selected events are mostly backgrounds such as W+jets and t{bar t} events, which we separate from the expected signals using three multivariate analysis techniques: boosted decision trees, Bayesian neural networks, and matrix element calculations. A binned likelihood fit of the signal cross section plus background to the data from the combination of the results from the three analysis methods gives a cross section for single top quark production of [sigma](p{bar p} → tb + X, tqb + X) = 4.7 ± 1.3 pb. The probability to measure a cross section at this value or higher in the absence of signal is 0.014%, corresponding to a 3.6 standard deviation significance. The measured cross section value is compatible at the 10% level with the standard model prediction for electroweak top quark production. We use the cross section measurement to directly determine the Cabibbo-Kobayashi-Maskawa quark mixing matrix element that describes the Wtb coupling and find.

Download or read book Review of Top Quark Physics Results written by and published by . This book was released on 2007 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the heaviest known fundamental particle, the top quark has taken a central role in the study of fundamental interactions. Production of top quarks in pairs provides an important probe of strong interactions. The top quark mass is a key fundamental parameter which places a valuable constraint on the Higgs boson mass and electroweak symmetry breaking. Observations of the relative rates and kinematics of top quark final states constrain potential new physics. In many cases, the tests available with study of the top quark are both critical and unique. Large increases in data samples from the Fermilab Tevatron have been coupled with major improvements in experimental techniques to produce many new precision measurements of the top quark. The first direct evidence for electroweak production of top quarks has been obtained, with a resulting direct determination of V{sub tb}. Several of the properties of the top quark have been measured. Progress has also been made in obtaining improved limits on potential anomalous production and decay mechanisms. This review presents an overview of recent theoretical and experimental developments in this field. We also provide a brief discussion of the implications for further efforts.

Download or read book 100 Years of Fundamental Theoretical Physics in the Palm of Your Hand written by E. B. Manoukian and published by Springer Nature. This book was released on 2020-10-20 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book aims to integrate, in a pedagogical and technical manner, with detailed derivations, all essential principles of fundamental theoretical physics as developed over the past 100 years. It covers: Quantum physics and Stability Problems in the Quantum World, Minkowski Spacetime Physics Particle Classifications and Underlying Symmetries, Symmetry Violations, Quantum Field Theory of Particle Interactions, Higgs Field Physics, Supersymmetry: A Theory with Mathematical Beauty Superstrings, Gravity and Supergravity, General Relativity Predictions, including Frame Dragging, Intricacies of Black Hole Physics, Perturbative and Non-perturbative Quantum Gravity Intricacies of Modern Cosmology, including Inflation and Power Spectrum If you are in the process of learning, or are lecturing on, any of the subjects above, then this is your book - irrespective of your specialty. With over-specialization and no time to master all the fields given above, students, and perhaps many physicists, may find it difficult to keep up with all the exciting developments going on, and are even less familiar with their underlying technicalities: e.g. they might have heard that the Universe is 13.8 billion years old, but have no idea on how this number is actually computed. This unique book will be of great value to graduate students, instructors and researchers interested in the intricacies and derivations of the many aspects of modern fundamental theoretical physics. And, although a graduate level book, some chapters may also be suitable for advanced undergraduates in their final year.

Download or read book Uncovering the Single Top written by Jorge Armando Benitez and published by . This book was released on 2009 with total page 724 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Expected Performance of the ATLAS Experiment written by and published by . This book was released on 2009 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: