Quarks And Leptons. An Introductory Course In Modern Particle Physics

421 Pages·1984·18.646 MB·English

by  Francis Halzen, Alan D. Martin

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QUARKS AND LEPTONS:
An Introductory Course
in Modern Particle Physics

QUARKS AND LEPTONS:
An Introductory Course
in Modern Particle Physics
FranHcailsz en
Univ_oefWirs sictoyn sin
MadisoWni,s consin
AlaDn.M artin
UniversoifDt uyrh am
DurhEanmg,la nd
JOHN WILEY & SONS,
New York Chichester Brisbane Toronto Singapore
Copyright© 1984, by John Wiley & Sons, Inc.
All rights reserved. Published simultaneously in Canada.
Reproduction or translation of any part of
this work beyond that permitted by Sections
107 and 108 of the 1976 United States Copyright
Act without the permission of the copyright
owner is unlawful. Requests for permission
or further information should be addressed to
the Permissions Department, John Wiley & Sons.
Libraryo fC ongreCastsa loginPugblica tini onD ata:
Halzen, Francis.
Quarks and leptons.
Includes index.
1. Quarks. 2. Leptons (Nuclear physics)
I. Martin, Alan D. (Alan Douglas) II. Title.
QC793.5.Q2522H34 1984 539.7'21 83-14649
ISBN 0-471-88741-2
Printed in the United States of America
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Preface
Dramatic progress has been made in particle physics during the past two decades.
A series of important experimental discoveries has firmly established the existence
of a subnuclear world of quarks and leptons. The protons and neutrons
("nucleons"), which form nuclei, are no longer regarded as elementary particles
but are found to be made of quarks. That is, in the sequence JllOlecules -+ atoms
-+ nuclei -+ nucleons, there is now known to be another "layer in the structure of
matter." However, the present euphoria in particle physics transcends this re­
markable discovery. The excitement is due to the realization that the dynamics of
quarks and leptons can be described by an extension of the sort of quantum field
theory that proved successful in describing the electromagnetic interactions of
charged particles. To be more precise, the fundamental interactions are widely
believed to be described by quantum field theories possessing local gauge symme­
try. One of the aims of this book is to transmit a glimpse of the amazing beauty
and power of these gauge theories. We discuss quarks and leptons, and explain
how they interact through the exchange of gauge field quanta (photons, gluons,
and weak bosons).
We are very conscious that this book has been written at a crucial time when
pertinent questions regarding the existence of the weak bosons and the stability of
the proton may soon be decided experimentally. Some sections of the book
should therefore be approached with a degree of caution, bearing in mind that the
promising theory of today may only be the effective phenomenology of the theory
of tomorrow. But no further apology will be made for our enthusiasm for gauge
theories.
We have endeavored to provide the reader with sufficient background to
understand the relevance of the present experimental assault upon the nature of
matter and to appreciate contemporary theoretical speculations. The required
core of knowledge is the standard electroweak model, which describes the electro­
magnetic and weak interactions of leptons and quarks; and quantum chromo­
dynamics (QCD), which describes the strong interactions of quarks and gluons.
The primary purpose of this book is to introduce these ideas in the simplest
possible way. We assume only a basic knowledge of nonrelativistic quantum
mechanics and the theory of special relativity. We spend considerable time
introducing quantum electrodynamics (QED) and try to establish a working
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