Quarks Baryons And Chiral Symmetry

This book describes baryon models constructed from quarks, mesons and chiral symmetry. The role of chiral symmetry and of quark model structure with SU(6) spin-flavor symmetry are discussed in detail, starting from a pedagogic introduction. Emphasis is placed on symmetry aspects of the theories. As an application, the chiral bag model is studied for nucleon structure, where important methods of theoretical physics, mostly related to the semiclassical approach for a system of strong interactions, are demonstrated. The text is more practical than formal; tools and ideas are explained in detail while solving actual problems. By checking each step of the computations, readers can learn not only the calculational techniques but also the essential ideas behind them.

The structure of light hadrons is dominated by the spontaneously broken chiral symmetry of the strongly interacting (QCD) vacuum. Low energy properties of light hadrons can be described in terms of quarks interacting with chiral fields. This book gives a comprehensive account of a large class of models which describe the restoration of chiral symmetry at high temperature and density, the effective interactions between quarks, mesons as solutions of the Beth-Salpeter equation, and baryons in terms of solitions which rotate in flavor space. An in-depth analysis of regularization is given, including regularization by delocalized fields. Symmetry conserving approximations are formulated using both path integral and Feynmann graph methods. The book's style is pedagogical and well-suited to graduate and Ph.D. students who want to learn the techniques used in present day research. It can also serve as a reference for research and lecture courses.

Ch. 1. Ingredients of the standard model. 1.1. Strong interaction - QCD. 1.2. Electroweak theory. 1.3. CKM mass matrix -- ch. 2. Symmetries and wave functions. 2.1. Why is symmetry important? 2.2. Symmetry current. 2.3. SU(2). 2.4. SU(3). 2.5. Multi-particle states. 2.6. Product-states. 2.7. Quark model wave functions -- ch. 3. Chiral symmetry. 3.1. Lorentz group and chiral fermions. 3.2. Chiral group. 3.3. Spontaneous breaking of chiral symmetry -- ch. 4. The sigma model. 4.1. Linear sigma model. 4.2. Non-linear sigma model. 4.3. Fermion field -- ch. 5. Chiral bag model. 5.1. The MIT bag model. 5.2. The little bag model. 5.3. The Skyrme model. 5.4. The chiral bag model. 5.5. Chiral casimir effects. 5.6. The edgehog solution -- ch. 6. Nucleon properties. 6.1. Semiclassical method. 6.2. Isospin rotation of the hedgehog solution. 6.3. Axial properties. 6.4. Non-rigid quantization of the skyrmion. 6.5. Electromagnetic properties. 6.6. Chiral bag with vector mesons -- ch. 7. Large-Nc baryons. 7.1. Introduction. 7.2. General counting rules. 7.3. Counting rules for solitons. 7.4. Large-Nc algebra for baryons. 7.5. Finite Nc. 7.6. Other representations and gA -- ch. 8. Excited baryons. 8.1. Systematics in baryon masses. 8.2. Quarks in a deformed oscillator potential. 8.3. Electromagnetic transitions.

At a fundamental level, the interaction of quarks with gluon fields lies at the heart of our understanding of the strong nuclear force. Experimentally, however, we only observe physical hadrons such as protons and pions. This book explores the fascinating physics involved in the path between these contrasting pictures of the world. Along the way, the book discusses symmetries, which play a crucial role in understanding the parameters of the theory, and details of the spectrum of physical particles.This would be the first book to elaborate on the detailed connections between confinement and chiral symmetry, with an emphasis on a unified treatment of the non-perturbative nature of these phenomena. As such, it should be a valuable title on any particle theorist's bookshelf, containing extensive pedagogical material for scientists at the graduate level and above.

This revised and extended edition of the book Fields, Symmetries, and Quarks, originally published by McGraw-Hill Book Company, Hamburg, 1989, contains a new chapter on electroweak interactions which has also grown out of lectures that I have given in the meantime. In addition, a number of changes, mainly in the metric used, in the discussion of the theory of strong interactions, QCD, and in the chapter on hadron physics, have been made and errors have been corrected. The motivation for this book, however, is still the same as it was 10 years ago: This is a book on quantum field theory and our present understanding of leptons and hadrons for advanced students and the non-specialists and, in particular, the experimentalists working on problems of nuclear and hadron physics. I am grateful to Dr. S. Leupold for a very careful reading of the revised manuscript, many corrections, and helpful suggestions and to C. Traxler for producing the figures and for constructive discussions.

Contents:Constituents of the Atomic Nucleus (B Povh)Quarks, Chiral Symmetry and Dynamics of Nuclear Constituents (W Weise)The Chiral Quark Bag: Properties and Spectroscopy of Baryons and the Nuclear Force (F Myhrer)Building the Nucleus from Quarks: the Cloudy Bag Model and the Quark Description of the Nucleon- Nucleon Wave Function (G A Miller)Deep Inelastic Lepton- Nucleus Scattering (H J Pirner)Baryon-baryon Interaction from Quark Model Viewpoint (M Oka & K Yazaki)From Phenomenological to Macroscopic Description of NN Annihilation (A M Green & J A Niskanen) Readership: Nuclear physicists. Keywords:Quarks;Nuclei;Chiral Symmetry;Dynamics;Baryons

These notes give an introduction to the description of hadrons, i.e., mesons and baryons, within a quark model based on a chirally invariant quantum field theory. Emphasis is put on a didactic approach intended for graduate students with some background on functional integral techniques. Starting from QCD a motivation of a specific form of the effective quark interaction is given. Functional integral bosonization leads to a theory describing successfully meson properties. It possesses solitonic solutions which are identified as baryons. Via functional integral techniques a Faddeev equation for baryons describing them as bound states of a diquark and a quark is derived. Finally, a unification of these two complementary pictures of baryons is proposed.