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 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.

This thesis focuses on an unresolved problem in particle and nuclear physics: the relation between two important non-perturbative phenomena in quantum chromodynamics (QCD) – quark confinement and chiral symmetry breaking. The author develops a new analysis method in the lattice QCD, and derives a number of analytical formulae to express the order parameters for quark confinement, such as the Polyakov loop, its fluctuations, and the Wilson loop in terms of the Dirac eigenmodes closely related to chiral symmetry breaking. Based on the analytical formulae, the author analytically as well as numerically shows that at finite temperatures there is no direct one-to-one correspondence between them. The thesis describes this extraordinary achievement using the first-principle analysis, and proposes a possible new phase in which quarks are confined and chiral symmetry is restored.

The 20-year-old problem of the confinement and the resulting spectrum of the bound states is central to quantum chromodynamics (QCD). Many approaches have been tried starting from different points of view: the potential theory, the Bethe-Salpeter equation, string and flux tube models, bag models, vacuum structure, current algebra, lattice theory, and numerical simulations. Phenomenological assumptions and first-principle theoretical results or indications have been combined. Many partial successes have been attained, but a unified and comprehensive treatment is still lacking.In recent years, new attention has been given to the problem, both in terms of theoretical developments and for the purpose of evaluating the spectrum and other properties of the particles. In particular, attention has been focussed on areas like numerical simulations, the derivation of the potential, the use of the Bethe-Salpeter equation, the connection between the potential and the chiral symmetry approach.This workshop was an opportunity for a synthesis and a comparison of the different points of view.

V N Gribov, one of the founders of modern particle physics, shaped our understanding of QCD as the microscopic dynamics of hadrons. This volume collects his papers on quark confinement, showing the road he followed to arrive at the theory and formulating the theory itself. It begins with papers providing a beautiful physical explanation of asymptotic freedom based on the phenomenon of antiscreening and demonstrating the inconsistency of the standard perturbative treatment of the gluon fields (Gribov copies, Gribov horizon). It continues with papers presenting the Gribov theory according to which confinement of colour is determined by the existence of practically massless quarks. The last two papers conclude Gribov's twenty-year-long study of the problem; QCD is formulated as a quantum field theory containing both perturbative and nonperturbative phenomena, and the confinement is based on the supercritical binding of light quarks.

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.