Electroweak theory

261 Pages·2010·2.467 MB·English

by  Paschos, Emmanuel A

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ELECTROWEAK THEORY
The electroweak theory unifies two basic forces of nature: the weak force and
electromagnetism. This achievement is comparable to Maxwell’s unification of
electricity and magnetism. The theory made numerous predictions that have been
confirmed by experiments. This book is a concise introduction to the structure of
theelectroweaktheoryanditsapplications.
Electroweak Theory describes the structure and properties of field theories with
globalandlocalsymmetries,leadingtotheconstructionofthestandardmodel.The
greater part of the book explains the basic predictions of the theory. It describes
the new particles and processes predicted by the theory, and compares them with
experimentalresults.Amongthetopicscoveredareneutralcurrents,theproperties
ofWandZbosons,thepropertiesofquarksandmesonscontainingheavyquarks,
neutrinooscillations,CP-asymmetriesinK,D,andBmesondecays,andthesearch
forHiggsparticles.
Thebookcontainssectionsguidingthereaderthroughthecomplicatedcalculations
of Feynman diagrams, such as box and penguin diagrams. There are discussions
of the results and their relevance to physical phenomena. Each chapter contains
selected problems, stemming from the long teaching experience of the author,
to supplement the text. This will be of great interest to graduate students and
researchers in elementary particle physics. Password protected solutions will be
availabletolecturersatwww.cambridge.org/9780521880987.
Emmanuel Paschos is Professor of Physics at the University of Dortmund,
Germany.HeisaFellowoftheAmericanPhysicalSocietyandoftheInstitutefor
AdvancedStudy,andacorrespondingmemberoftheAcademyofAthens.

ELECTROWEAK THEORY
E. A. PASCHOS
UniversityofDortmund
CAMBRIDGEUNIVERSITYPRESS
Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo
Cambridge University Press
The Edinburgh Building, Cambridge CB2 8RU, UK
Published in the United States of America by Cambridge University Press, New York
www.cambridge.org
Information on this title: www.cambridge.org/9780521860987
©E.Paschos2007
This publication is in copyright. Subject to statutory exception and to the provision of
relevant collective licensing agreements, no reproduction of any part may take place
without the written permission of Cambridge University Press.
First published in print format 2007
ISBN-13 978-0-511-27156-4 eBook (Adobe Reader)
ISBN-10 0-511-27156-5 eBook (Adobe Reader)
ISBN-13 978-0-521-86098-7 hardback
ISBN-10 0-521-86098-9 hardback
Cambridge University Press has no responsibility for the persistence or accuracy of urls
for external or third-party internet websites referred to in this publication, and does not
guaranteethatanycontentonsuchwebsitesis,orwillremain,accurateorappropriate.
TomywifeSharon
andourchildren
Anthony,Christina-Maria,andJohn

Contents
Preface pagexi
PartI Theroadtounification 1
1 Theelectromagneticcurrentanditsproperties 3
1.1 Introduction 3
1.2 Thecurrentforhadronicstates 6
1.3 Parity-violatingformfactors 9
References 10
Selectbibliography 11
2 Theweakcurrents 12
2.1 Theweakcurrentsandsomeoftheirproperties 12
2.2 Thepartiallyconservedaxialcurrent 16
2.3 Regularitiesamongtheforces 18
ProblemsforChapters1and2 19
References 19
Selectbibliography 20
3 Thequarkmodel 21
3.1 Introduction 21
3.2 Currentalgebra 22
3.3 Quantumchromodynamics 26
ProblemsforChapter3 28
References 28
Selectbibliography 29
PartII Fieldtheorieswithglobalorlocalsymmetries 31
4 Yang–Millstheories 33
4.1 TheYang–Millsfield 33
4.2 Gaugeinvarianceinscalarelectrodynamics 36
vii
viii Contents
ProblemsforChapter4 39
Selectbibliography 40
5 Spontaneousbreakingofsymmetries 41
5.1 Spontaneousbreakingofglobalsymmetries:discretesymmetry 42
5.2 Continuousglobalsymmetries 44
5.3 Spontaneousbreakingoflocalsymmetries 49
ProblemsforChapter5 51
Selectbibliography 52
6 Constructionofthemodel 53
Selectbibliography 56
7 TheHiggsmechanismintheGlashow–Salam–Weinbergmodel 57
7.1 Massesforgaugebosons 57
7.2 Massesforleptons 61
ProblemsforChapter7 62
References 62
Selectbibliography 62
8 Theleptonicsector 64
8.1 Feynmanrules 64
8.2 Predictionsintheleptonicsector 68
8.3 Leptonicneutralcurrents 70
8.4 Weakeffectsinelectron–positronannihilation 76
ProblemforChapter8 77
9 Incorporatinghadrons 78
9.1 Themixingmatrix 78
9.2 Flavor-changingneutralcouplings(FCNCs) 82
9.3 Theelementsofthemixingmatrix 84
References 92
Selectbibliography 92
PartIII Experimentalconsequencesandcomparisons 93
10 Deepinelasticscattering 95
10.1 Kinematicsfordeepinelasticscattering 95
10.2 Hadronicstructurefunctions 99
10.3 Scalingandthetotalcrosssection 101
10.4 Thepartonmodel 104
10.5 TheDrell–Yanprocess 108
ProblemsforChapter10 110
References 111
11 Charged-currentreactions 112
11.1 Deepinelasticscattering 112
11.2 Evolutionofdistributionfunctions 117