Top Quark Pair Production
Top Quark Pair Production

Author: Anna Christine Henrichs

Publisher: Springer Science & Business Media

Published: 2013-10-04

Total Pages: 231

ISBN-13: 3319014870

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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.

Measurement of the Top Quark Mass in the Dilepton Final State Using the Matrix Element Method
Measurement of the Top Quark Mass in the Dilepton Final State Using the Matrix Element Method

Author: Alexander Grohsjean

Publisher: Springer Science & Business Media

Published: 2010-10-01

Total Pages: 155

ISBN-13: 364214070X

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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.

Top-Quark Pair Production Cross Sections and Calibration of the Top-Quark Monte-Carlo Mass
Top-Quark Pair Production Cross Sections and Calibration of the Top-Quark Monte-Carlo Mass

Author: Jan Kieseler

Publisher: Springer

Published: 2016-06-15

Total Pages: 172

ISBN-13: 3319400053

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This thesis presents the first experimental calibration of the top-quark Monte-Carlo mass. It also provides the top-quark mass-independent and most precise top-quark pair production cross-section measurement to date. The most precise measurements of the top-quark mass obtain the top-quark mass parameter (Monte-Carlo mass) used in simulations, which are partially based on heuristic models. Its interpretation in terms of mass parameters used in theoretical calculations, e.g. a running or a pole mass, has been a long-standing open problem with far-reaching implications beyond particle physics, even affecting conclusions on the stability of the vacuum state of our universe. In this thesis, this problem is solved experimentally in three steps using data obtained with the compact muon solenoid (CMS) detector. The most precise top-quark pair production cross-section measurements to date are performed. The Monte-Carlo mass is determined and a new method for extracting the top-quark mass from theoretical calculations is presented. Lastly, the top-quark production cross-sections are obtained – for the first time – without residual dependence on the top-quark mass, are interpreted using theoretical calculations to determine the top-quark running- and pole mass with unprecedented precision, and are fully consistently compared with the simultaneously obtained top-quark Monte-Carlo mass.

Top Quark Physics at Hadron Colliders
Top Quark Physics at Hadron Colliders

Author: Arnulf Quadt

Publisher: Springer Science & Business Media

Published: 2007-08-16

Total Pages: 166

ISBN-13: 3540710604

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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.

Spin Correlations in tt Events from pp Collisions
Spin Correlations in tt Events from pp Collisions

Author: Boris Lemmer

Publisher: Springer

Published: 2015-06-24

Total Pages: 246

ISBN-13: 3319189328

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This thesis introduces readers to the Standard Model, the top quark and its properties, before explaining the concept of spin correlation measurement. The first measurement of top quark spin correlations at the LHC in the lepton+jets decay channel is presented. As the heaviest elementary particle, the top quark plays an essential role in the Standard Model of elementary particle physics. In the case of top quarks being produced in pairs at hadron colliders, the Standard Model predicts their spins to be correlated. The degree of correlation depends on both the production mechanism and properties of the top quark. Any deviation from the Standard Model prediction can be an indicator for new physics phenomena. The thesis employs an advanced top quark reconstruction algorithm including dedicated identification of the up- and down-type quarks from the W boson decay.

Proceedings of the 31st International Conference on High Energy Physics ICHEP 2002
Proceedings of the 31st International Conference on High Energy Physics ICHEP 2002

Author: S. Bentvelsen

Publisher: Elsevier

Published: 2012-12-02

Total Pages: 1004

ISBN-13: 0444599169

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The first precision measurements on CP violation in the B system are reported. Both the BELLE and the BABAR collaboration presented, among others, results for sin 2ß with much improved accuracy. Results from the Sudbury Neutrino Observatory, SNO, also deserve to be mentioned. The convincing evidence of solar neutrino oscillations had been presented by SNO prior to the conference; a full presentation was given at the conference. An incredibly precise measurement of the anomalous magnetic moment of the muon is reported, a fresh result from the Brookhaven National Laboratory. Apart from these distinct physics highlights, there are also the first results from the new Tevatron run and from the relativistic heavy ion collider RHIC. Theorists write of our ever better understanding of the Standard Model and of what might lie beyond. Risky as it is to highlight only a couple of exciting subjects, it is merely meantto whet the appetite for further reading.

Lepton Photon Interactions At High Energies (Lepton Photon 2017) - Proceedings Of The 28th International Symposium
Lepton Photon Interactions At High Energies (Lepton Photon 2017) - Proceedings Of The 28th International Symposium

Author: Wei Wang

Publisher: World Scientific

Published: 2020-02-27

Total Pages: 576

ISBN-13: 9811207410

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The latest of the 'Lepton Photon' symposium, one of the well-established series of meetings in the high-energy physics community, was successfully organized at the South Campus of Sun Yat-sen University, Guangzhou, China, from August 7-12, 2017, where physicists around the world gathered to discuss the latest advancements in the research field.This proceedings volume of the Lepton Photon 2017 collects contributions by the plenary session speakers and the posters' presenters, which cover the latest results in particle physics, nuclear physics, astrophysics, cosmology, and plans for future facilities.