A Precision Measurement of the Z0 Lineshape Parameters for the Process Z0 2![tau]+[tau]-

A Precision Measurement of the Z0 Lineshape Parameters for the Process Z0 2![tau]+[tau]-

Author:

Publisher:

Published: 1996

Total Pages: 283

ISBN-13:

DOWNLOAD EBOOK

In this dissertation, a measurement of the partial decay width of the process Z0 → [tau]+[tau]- using data collected during 1993 and 1994 at the OPAL detector at CERN is described. The cross sections of this process at three center-of-mass energies near the Z0 resonance were determined, and from a fit to those cross sections, the mass of the Z0, its total decay width and its partial decay width into [tau]+[tau]- final states were determined as MZ = 91.183 ± 0.020 GeV, [Gamma]tot = 2.514 ± 0.018 GeV and [Gamma][tau][tau] = 84.54 ± 0.59 MeV. Using published results for MZ, and [Gamma]tot with higher accuracy, a value for the partial decay width of [Gamma][tau][tau] = 84.02 ± 0.20 MeV was obtained. Further using published results for the decay width of the Z0 into quark pair final states, the invisible decay width of the Z0 was determined as [Gamma]inv = 496.9 ± 4.1 MeV, and the number of neutrino generations was determined as Nv = 2.974 ± 0.025(exp) ± 0.007 (mtop, MHiggs). All results were found to be in good agreement with the Standard Model predictions and were consistent with the assumption of lepton universality within the Standard Model framework.


Astronomical Distance Determination in the Space Age

Astronomical Distance Determination in the Space Age

Author: Richard de Grijs

Publisher: Springer

Published: 2019-02-13

Total Pages: 0

ISBN-13: 9789402416305

DOWNLOAD EBOOK

Knowing the distance of an astrophysical object is key to understanding its formation and evolution. Without an accurate distance, we do not know how bright it is, how large it is, or even when it existed. This volume highlights the tremendous amount of recent and continuing research into a myriad of exciting and promising aspects of accurately pinning down the cosmic distance scale, where possible focused on space-based contributions. These papers go one step further, putting the many recent results and new developments into the broader context of the physics driving cosmic distance determination. Thus, the volume will benefit researchers spanning a wide range of expertise, including theorists, observers, and modelers working on a large variety of spatial scales. Originally published in Space Science Reviews in the Topical Collection "Astronomical Distance Determination in the Space Age"


Classical and Quantum Molecular Dynamics in NMR Spectra

Classical and Quantum Molecular Dynamics in NMR Spectra

Author: Sławomir Szymański

Publisher: Springer

Published: 2018-05-24

Total Pages: 402

ISBN-13: 3319907816

DOWNLOAD EBOOK

The book provides a detailed account of how condensed-phase molecular dynamics are reflected in the line shapes of NMR spectra. The theories establishing connections between random, time-dependent molecular processes and lineshape effects are exposed in depth. Special emphasis is placed on the theoretical aspects, involving in particular intermolecular processes in solution, and molecular symmetry issues. The Liouville super-operator formalism is briefly introduced and used wherever it is beneficial for the transparency of presentation. The proposed formal descriptions of the discussed problems are sufficiently detailed to be implemented on a computer. Practical applications of the theory in solid- and liquid-phase studies are illustrated with appropriate experimental examples, exposing the potential of the lineshape method in elucidating molecular dynamics NMR-observable molecular phenomena where quantization of the spatial nuclear degrees of freedom is crucial are addressed in the last part of the book. As an introduction to this exciting research field, selected aspects of the quantum mechanics of isolated systems undergoing rotational tunnelling are reviewed, together with some basic information about quantum systems interacting with their condensed environment. The quantum theory of rate processes evidenced in the NMR lineshapes of molecular rotors is presented, and illustrated with appropriate experimental examples from both solid- and liquid-phase spectra. In this context, the everlasting problem of the quantum-to-classical transition is discussed at a quantitative level. The book will be suitable for graduate students and new and practising researchers using NMR techniques.


The Physics of the B Factories

The Physics of the B Factories

Author: Adrian Bevan

Publisher: Springer

Published: 2015-03-23

Total Pages: 0

ISBN-13: 9783662449905

DOWNLOAD EBOOK

This comprehensive work thoroughly introduces and reviews the set of results from Belle and BaBar - after more than two decades of independent and complementary work - all the way from the detectors and the analysis tools used, up to the physics results, and the interpretation of these results. The world’s two giant B Factory collaborations, Belle at KEK and BaBar at SLAC, have successfully completed their main mission to discover and quantify CP violation in the decays of B mesons. CP violation is a necessary requirement to distinguish unambiguously between matter and antimatter. The shared primary objective of the two B Factory experiments was to determine the shape of the so-called unitarity triangle, an abstract triangle representing interactions of quarks, the elementary constituents of matter. The area of the triangle is a measure of the amount of CP violation associated with the weak force. Many other measurements have been performed by the B Factories and are also discussed in this work.


Fundamentals Of Electroweak Theory (Second Edition)

Fundamentals Of Electroweak Theory (Second Edition)

Author: Jiri Horejsi

Publisher: World Scientific

Published: 2024-06-11

Total Pages: 379

ISBN-13: 9811291683

DOWNLOAD EBOOK

This book is based on the lecture course taught by the author for about three decades at Charles University. The author gives a thorough and easy-to-read account of the basic principles of the standard model of electroweak interactions, describes various theories of electromagnetic and weak interactions, and explains the gauge theory of electroweak interactions. The criterion of the tree-level unitarity is used throughout the text to check the gradual steps leading to the renormalizable electroweak theory. Five appendices expound on some special techniques of the Standard Model, used in the main body of the text.The book can be read with just a preliminary knowledge of quantum field theory. In comparison with the first edition of the book published more than 20 years ago, new passages concerning the Higgs boson are added, as well as some new problems and solutions.


The Standard Model in the Making

The Standard Model in the Making

Author: D. Bardin

Publisher: Oxford University Press

Published: 1999

Total Pages: 708

ISBN-13: 9780198502807

DOWNLOAD EBOOK

The standard model in particle physics unifies the theories of electromagnetic and weak interactions. Much work has been over the last decade, and this book describes some of the leading experimental tests of the model. It is unique in collecting in one volume all of the formulas, recipes, and prescriptions necessary for testing the theory and will be an invaluable tool as experiments move into higher energies. It aims to give a comprehensive exposition of the foundations of the Standard Model and its applications to high energy phenomena.