Elementary particle physics is the quadrant of nature whose laws can be written in a few lines with absolute precision and the greatest empirical adequacy. The lectures presented in this book introduce students and interested readers to the entire subject in a compact way. It details the current theory of ElectroWeak interactions after one year of operation of the Large Hadron Collider at CERN in Geneva, focusing on open questions that the experiments might allow to answer.

The papers contained in this volume are invited lec tures presented at the 21st "Universit~tswochen fUr Kern physik" in Schladming in February 1982. To consider electro magnetic and weak interactions as manifestations of a single theory is a standpoint, which is generally accepted by now. The goal of the school was to outline the present state of this unified theory and to discuss possible future developments. Thanks to the generous support provided by the Austrian Ministry of Science and Research, the Styrian Government and other sponsors, it was again possible to invite experts in the field as lecturers. The lecture notes have been reexamined by the authors and are now published in their final form to enable a larger number of physicists to profit from them. Since the lectures are already quite voluminous, we have decided to restrict the publication to the lectures themselves and omit all seminars, interesting as they were, as well as all details connected with the meeting. It is a pleasure to thank all the lecturers for their efforts, making it possible to speed up publication. Thanks are also due to L. Pittner for organisation and proof-reading as well as to Mrs. Krenn and Mrs. Neuhold for the careful typing of the papers. H. Mitter Acta Physica Austriaca, Suppl. XXIV, 3-62 (1982) © by Springer-Verlag 1982 INTRODUCTION TO GAUGE THEORIES OF ELECTRO + WEAK INTERACTIONS by G. ECKER Institut fUr Theoretische Physik Universitat Wien, Austria TABLE OF CONTENTS I

For many years neutrino was considered a massless particle. The theory of a two-componentneutrino,whichplayedacrucialroleinthecreationofthetheoryof theweakinteraction,isbasedontheassumptionthattheneutrinomassisequalto zero. We now know that neutrinos have nonzero, small masses. In numerous exp- iments with solar, atmospheric, reactor and accelerator neutrinos a new p- nomenon, neutrino oscillations, was observed. Neutrino oscillations (periodic transitionsbetweendifferent?avorneutrinos? ,? ,? )arepossibleonlyifneutrino e ? ? mass-squareddifferencesaredifferentfromzeroandsmalland?avorneutrinosare “mixed”. The discovery of neutrino oscillations opened a new era in neutrino physics: an era of investigation of neutrino masses, mixing, magnetic moments and other neutrino properties. After the establishment of the Standard Model of the el- troweak interaction at the end of the seventies, the discovery of neutrino masses was the most important discovery in particle physics. Small neutrino masses cannot be explained by the standard Higgs mechanism of mass generation. For their explanation a new mechanism is needed. Thus, small neutrino masses is the ?rst signature in particle physics of a new beyond the Standard Model physics. It took many years of heroic efforts by many physicists to discover n- trino oscillations. After the ?rst period of investigation of neutrino oscillations, manychallengingproblemsremainedunsolved.Oneofthemostimportantisthe problem of the nature of neutrinos with de?nite masses. Are they Dirac n- trinos possessing a conserved lepton number which distinguish neutrinos and antineutrinos or Majorana neutrinos with identical neutrinos and antineutrinos? Many experiments of the next generation and new neutrino facilities are now under preparation and investigation. There is no doubt that exciting results are ahead.

Supernovae explosion, combustion of solar hydrogen to form helium, heavy quark decay, or nuclear beta radiation, all weak interaction phenomena, are not unrelated to electromagnetism, but closely linked to it through the Higgs field. This ebook contains a modern introduction to the electroweak unification theory, as part of the so called Standard Model of particle physics. Not only some of the key theoretical ideas are exposed in a precise way, but also the experiments that revealed them. The main highlights of the theory consolidation process are examined which, concerning its experimental counterpart, span over 40 years, from the discovery of neutral currents in1973 to the Higgs boson in 2012. The reader is assumed to have been introduced to Quantum Mechanics and theories based on the gauge invariance principle, and to be familiar with Dirac’s theory for the relativistic electron. The course is specially suited for undergraduate students in physics, as part of an optional subject of elementary particles. The course consists in nine lectures, that on the blackboard take about 90 minutes each. It contains a very select collection of problems and exercises, having as a connecting thread the calculation of the lifetime of elementary fermions and bosons, as well as the comprehension of some experimental results of historical relevance.

This book comprises the lectures of a two-semester course on quantum field theory, presented in a quite informal and personal manner. The course starts with relativistic one-particle systems, and develops the basics of quantum field theory with an analysis on the representations of the Poincaré group. Canonical quantization is carried out for scalar, fermion, Abelian and non-Abelian gauge theories. Covariant quantization of gauge theories is also carried out with a detailed description of the BRST symmetry. The Higgs phenomenon and the standard model of electroweak interactions are also developed systematically. Regularization and (BPHZ) renormalization of field theories as well as gauge theories are discussed in detail, leading to a derivation of the renormalization group equation. In addition, two chapters — one on the Dirac quantization of constrained systems and another on discrete symmetries — are included for completeness, although these are not covered in the two-semester course.This second edition includes two new chapters, one on Nielsen identities and the other on basics of global supersymmetry. It also includes two appendices, one on fermions in arbitrary dimensions and the other on gauge invariant potentials and the Fock-Schwinger gauge.

"Unique in its coverage of all aspects of modern particle physics, this textbook provides a clear connection between the theory and recent experimental results, including the discovery of the Higgs boson at CERN. It provides a comprehensive and self-contained description of the Standard Model of particle physics suitable for upper-level undergraduate students and graduate students studying experimental particle physics. Physical theory is introduced in a straightforward manner with full mathematical derivations throughout. Fully-worked examples enable students to link the mathematical theory to results from modern particle physics experiments. End-of-chapter exercises, graded by difficulty, provide students with a deeper understanding of the subject. Online resources available at www.cambridge.org/MPP feature password-protected fully-worked solutions to problems for instructors, numerical solutions and hints to the problems for students and PowerPoint slides and JPEGs of figures from the book"--

Gauge Theory of Weak Interactions treats the unification of electromagnetic and weak interactions and considers related phenomena. First, the Fermi theory of beta decay is presented, followed by a discussion of parity violation, clarifying the importance of symmetries. Then the concept of a spontaneously broken gauge theory is introduced, and all necessary mathematical tools are carefully developed. The "standard model" of unified electroweak interactions is thoroughly discussed including current developments. The final chapter contains an introduction to unified theories of strong and electroweak interactions. Numerous solved examples and problems make this volume uniquely suited as a text for an advanced course. Thisfourth edition has been carefully revised.