Introduction to Physics of Elementary Particles

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Introduction to Physics of Elementary Particles INTRODUCTION TO PHYSICS OF ELEMENTARY PARTICLES INTRODUCTION TO PHYSICS OF ELEMENTARY PARTICLES O.M. BOYARKIN Nova Science Publishers, Inc. New York c 2007 by Nova Science Publishers, Inc. All rights reserved. No part of this book may be reproduced, stored in a retrieval system or transmitted in any form or by any means: electronic, electrostatic, magnetic, tape, mechanical photocopying, recording or otherwise without the written permission of the Publisher. For permission to use material from this book please contact us: Telephone 631-231-7269; Fax 631-231-8175 Web Site: http://www.novapublishers.com NOTICE TO THE READER The Publisher has taken reasonable care in the preparation of this book, but makes no expressed or implied warranty of any kind and assumes no responsibility for any errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of information contained in this book. The Publisher shall not be liable for any special, consequential, or exemplary damages resulting, in whole or in part, from the readers’ use of, or reliance upon, this material. Independent verification should be sought for any data, advice or recommendations contained in this book. In addition, no responsibility is assumed by the publisher for any injury and/or damage to persons or property arising from any methods, products, instructions, ideas or otherwise contained in this publication. This publication is designed to provide accurate and authoritative information with regard to the subject matter cover herein. It is sold with the clear understanding that the Publisher is not engaged in rendering legal or any other professional services. If legal, medical or any other expert assistance is required, the services of a competent person should be sought. FROM A DECLARATION OF PARTICIPANTS JOINTLY ADOPTED BY A COMMITTEE OF THE AMERICAN BAR ASSOCIATION AND A COMMITTEE OF PUBLISHERS. Library of Congress Cataloging-in-Publication Data Available upon request ISBN 978-1-60692-598-0 Published by Nova Science Publishers, Inc. New York In the textbook all the known types of fundamental interactions are considered. The main directions of their unification are viewed. The basic theoretical ideas and the basic exper- iments, which allow to establish a quark-lepton level of a matter structure, are discussed. The general scheme of building up the theory of interacting fields with the help of the local gauge invariance principle is given. This scheme is used under presentation of the basic aspects of the quantum chromodynamics and the electroweak theory by Weinberg-Salam- Glashow. Principles of operation and designs of accelerators, neutrino telescopes, and ele- mentary particle detectors are considered. The modern theory of the Universe evolution is described. The textbook is primarily meant for Physics Department students. The book also will be useful to teachers, researches, post-graduate students and to all who are interested in problems of a modern physics. Contents Preface xi 1 Interactions and Ways of Their Unification 1 1.1.StrongInteraction............................... 1 1.2.ElectromagneticInteraction.......................... 4 1.3.WeakInteraction............................... 5 1.4.GravitationInteraction............................ 7 1.5. Grand UnifiedTheory............................. 12 1.6.Supersymmetry................................ 16 1.7.Supergravitation................................ 17 1.8.Kaluza-KleinTheory............................. 17 1.9.SuperstringTheory.............................. 20 2 Three Steps of Quantum Stairway 23 2.1.AtomicTheory................................ 23 2.2.NuclearModelofAtom............................ 25 2.3.Proton-NeutronModelofAtomNucleus................... 33 3 Leptons and Hadrons 37 4 Periodic Table of Hadrons 43 4.1. Yukawa Hypothesis .............................. 43 4.2.FeynmanDiagrams.............................. 48 4.3.ElementsoftheGroupTheory........................ 51 4.4. Isotopic Multiplets .............................. 62 4.5.Resonances.................................. 71 4.6. Unitary Multiplets ............................... 77 4.7. SU(3)-Symmetry............................... 82 5 Quark-Lepton Level of Matter Structure 95 5.1.Quark”Atoms”................................ 95 5.2.ElasticFormfactorsofNucleons.......................100 5.3.BjorkenScaling................................118 5.4.PartonModel.................................123 5.5.Color.....................................126 ix x Contents 5.6. c-Quark and SU(4)-Symmetry........................135 5.7. b and t-Quarks................................139 5.8. Looking for Free Quarks ...........................143 6 Standard Model 147 6.1.AbelianGaugeInvarianceandQCD.....................147 6.2.NonabelianGaugeInvarianceandQCD...................151 6.3. Spontaneous Symmetry Breaking. Higgs Mechanism . ...........153 6.4.Weinberg-Salam-GlashowTheory......................158 7 Fundamental Particles 173 8 Devices of Elementary Particle Physics 181 8.1. Particle Accelerators .............................181 8.2.ParticleDetectors...............................190 8.3.NeutrinoTelescopes..............................195 9 Macroworld 201 9.1.ModelsofUniverseEvolution........................201 9.2. Neutrino Astronomy .............................223 Epilogue 229 Appendix 231 References 233 Index 235 Preface The history of Physics is as abundant in shocks as a political life of a typical banana re- public, where babies learn the word ”revolution” immediately after the word ”mama”. At quiet times, however, physicists often have the illusion of complete understanding of the world. It was also the case in the beginning of the XXth century, when in the clear skies of Classical Physics there were only two small clouds, two unsolved problems, namely ether hypothesis and radiation spectrum of blackbody. The results of experiments by Mickelson and Morlet demonstrated that ether possesses no observable properties. They did not only ruin the ether theory altogether, but they also made the foundation of the special theory of relativity (STR), created by Einstein in 1905. In our opinion, there are two following aspects of the STR which form nowadays an education standard of any physicist and that is the highest price for any physical theory. The former aspect deals with understanding of properties belonging to the four dimensional space-time that surrounds us. The latter one reflects a deep faith in worldly wisdom of a correspondence principle, which reads: every new and more precise theory comprises in the utmost case the old and less exact theory. Thus, Newton’s classical mechanics was not wrong it simply turned out to be approximate theory. It is easy to check, that all of its formulae can be obtained from the corresponding expressions in the STR at passage to the limit c → ∞. When describing relativistic phenom- ena (v ∼ c), the correct answer can be given by the STR only. Max Plank’s explanation of radiation spectrum of blackbody was that very spark to stroke the flames of the second revo- lution in Physics which resulted in creation of non-relativistic quantum mechanics (NQM). This theory explained a matter structure at atomic and molecular levels with striking suc- cess. The Planck constant, the action quantum, plays the fundamental role in the NQM. As soon as any dynamic observables of the system having action dimension (energy×time) are comparable in their value with , classical physics ends in a fiasco and the right description can be obtained only within the NQM. Once again we can check, that familiar formulae of classical physics follow from their counterparts of the NQM at passage to the limit → 0. In 1915 Einstein’s general theory of relativity (GTR) succeeded classical theory of grav- itation. The GTR made a revolution both in methods and in the very contents of theoretical physics. Einstein discovered not only the new physical laws, but a new method of establish- ing the new laws as well. The GTR was based on the equivalent principle which suggested no difference between gravitation and acceleration in a small spatial domain. Unlike New- ton’s theory of gravitation, the GTR is not only a theory of gravitational interaction, but also a theory of space-time, consequently, a theory of the Universe in general. Non-stationary models of the Universe, obtained by Friedmann on the basis of the GTR equation solutions xii O.M. Boyarkin at that time seemed to be mere fantastic. However, as soon as 1929 astronomical obser- vations by A. Hubble proved the theory of the expanding Universe to be right. Thus, the Universe of Plato and Pifagor is succeeded by the Universe which has a starting point in time and neither beginning nor end in space. Merging of the STR and the NQM resulted in foundation of the quantum field the- ory, which constitutes the theoretical base of elementary particle physics. In the beginning it seemed that particle physics consisted of intuitive assumptions and set of recipes taken from ceiling. Each kind of fundamental interactions was studied separately, almost inde- pendently from other ones. The existence of divergences in the series of the perturbation theory was the only common trait, unifying all interactions. Only the theory of electromag- netic electron-positron interaction, the quantum electrodynamics, was a pleasant exception from such a dull landscape. The situation, however, changed abruptly by the beginning of the seventies in the XXth century. Velvet gauge revolution
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