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.


Search for tt̄H Production in the H → bb̅ Decay Channel

Search for tt̄H Production in the H → bb̅ Decay Channel

Author: Marcel Rieger

Publisher: Springer Nature

Published: 2021-02-25

Total Pages: 217

ISBN-13: 3030653803

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In 1964, a mechanism explaining the origin of particle masses was proposed by Robert Brout, François Englert, and Peter W. Higgs. 48 years later, in 2012, the so-called Higgs boson was discovered in proton-proton collisions recorded by experiments at the LHC. Since then, its ability to interact with quarks remained experimentally unconfirmed. This book presents a search for Higgs bosons produced in association with top quarks tt̄H in data recorded with the CMS detector in 2016. It focuses on Higgs boson decays into bottom quarks H → bb̅ and top quark pair decays involving at least one lepton. In this analysis, a multiclass classification approach using deep learning techniques was applied for the first time. In light of the dominant background contribution from tt̄ production, the developed method proved to achieve superior sensitivity with respect to existing techniques. In combination with searches in different decay channels, the presented work contributed to the first observations of tt̄H production and H → bb̅ decays.


CMS Pixel Detector Upgrade and Top Quark Pole Mass Determination

CMS Pixel Detector Upgrade and Top Quark Pole Mass Determination

Author: Simon Spannagel

Publisher: Springer

Published: 2017-08-01

Total Pages: 286

ISBN-13: 331958880X

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This thesis addresses two different topics, both vital for implementing modern high-energy physics experiments: detector development and data analysis. Providing a concise introduction to both the standard model of particle physics and the basic principles of semiconductor tracking detectors, it presents the first measurement of the top quark pole mass from the differential cross-section of tt+J events in the dileptonic tt decay channel. The first part focuses on the development and characterization of silicon pixel detectors. To account for the expected increase in luminosity of the Large Hadron Collider (LHC), the pixel detector of the compact muon solenoid (CMS) experiment is replaced by an upgraded detector with new front-end electronics. It presents comprehensive test beam studies conducted to verify the design and quantify the performance of the new front-end in terms of tracking efficiency and spatial resolution. Furthermore, it proposes a new cluster interpolation method, which utilizes the third central moment of the cluster charge distribution to improve the position resolution. The second part of the thesis introduces an alternative measurement of the top quark mass from the normalized differential production cross-sections of dileptonic top quark pair events with an additional jet. The energy measurement is 8TeV. Using theoretical predictions at next-to-leading order in perturbative Quantum Chromodynamics (QCD), the top quark pole mass is determined using a template fit method.


The Large Hadron Collider

The Large Hadron Collider

Author: Thomas Schörner-Sadenius

Publisher: Springer

Published: 2015-05-15

Total Pages: 554

ISBN-13: 3319150014

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This comprehensive volume summarizes and structures the multitude of results obtained at the LHC in its first running period and draws the grand picture of today’s physics at a hadron collider. Topics covered are Standard Model measurements, Higgs and top-quark physics, flavour physics, heavy-ion physics, and searches for supersymmetry and other extensions of the Standard Model. Emphasis is placed on overview and presentation of the lessons learned. Chapters on detectors and the LHC machine and a thorough outlook into the future complement the book. The individual chapters are written by teams of expert authors working at the forefront of LHC research.


Gauge Theories in Particle Physics 40th Anniversary Edition

Gauge Theories in Particle Physics 40th Anniversary Edition

Author: Ian J.R. Aitchison

Publisher: CRC Press

Published: 2024-08-06

Total Pages: 853

ISBN-13: 1040267890

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The fifth edition of this well-established, highly regarded two-volume set continues to provide a fundamental introduction to advanced particle physics while incorporating substantial new experimental results, especially in the areas of the Higgs and top quark sectors, as well as CP violation and neutrino oscillations. It offers an accessible and practical introduction to the three gauge theories comprising the Standard Model of particle physics: quantum electrodynamics (QED), quantum chromodynamics (QCD), and the Glashow-Salam-Weinberg (GSW) electroweak theory. The first volume provides a broad and self-contained introduction to the first of these theories, QED. A unique feature is the elementary introduction to quantum field theory, leading in easy stages to covariant perturbation theory and Feynman graphs, thereby establishing a firm foundation for the formal and conceptual framework upon which the subsequent development of the three quantum gauge field theories of the Standard Model is based. The second volume covers the two non-Abelian gauge theories of QCD and the GSW theory. A distinctive feature is the extended treatment of two crucial theoretical tools: spontaneous symmetry breaking and the renormalization group. The underlying physics of these is elucidated by parallel discussions of examples from condensed matter systems: superfluidity and superconductivity, and critical phenomena. This new edition includes updates to jet algorithms, lattice field theory, CP violation and the CKM matrix, and neutrino physics. New to the fifth edition: Tests of the Standard Model in the Higgs and top quark sectors The naturalness problem and responses to it going beyond the Standard Model The Standard Model as an effective field theory This revised and updated anniversary edition provides a self-contained pedagogical treatment of the subject, from relativistic quantum mechanics to the frontiers of the Standard Model. For each theory, the authors discuss the main conceptual points in both mathematical and physical aspects, detail many practical calculations of physical quantities from first principles, and compare these quantitative predictions with experimental results, helping readers improve both their calculation skills and physical insight. This set should serve as a valuable handbook for students and researchers in advanced particle physics looking for an introduction to the Standard Model of particle physics.


Particle Physics Reference Library

Particle Physics Reference Library

Author: Herwig Schopper

Publisher: Springer Nature

Published: 2020

Total Pages: 632

ISBN-13: 3030382079

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This first open access volume of the handbook series contains articles on the standard model of particle physics, both from the theoretical and experimental perspective. It also covers related topics, such as heavy-ion physics, neutrino physics and searches for new physics beyond the standard model. A joint CERN-Springer initiative, the "Particle Physics Reference Library" provides revised and updated contributions based on previously published material in the well-known Landolt-Boernstein series on particle physics, accelerators and detectors (volumes 21A, B1,B2,C), which took stock of the field approximately one decade ago. Central to this new initiative is publication under full open access