This book contains the proceedings of the Workshop on Nonperturbative Methods in Quantum Field Theory, held in Adelaide, Australia, in February 1998. Lattice gauge theory and calculations based on the use of Schwinger-Dyson equations feature prominently, with further contributions in the areas of variational and functional techniques, strong interaction phenomenology and chiral perturbation theory. QCD in the infrared regime as well as QCD at finite temperatures and densities is the subject matter of a number of papers, while other authors explore chiral symmetry breaking in QCD as well as in other field theories.

This workshop was devoted to a discussion of recent progress made in the understanding of quantum field theories in spacetimes of less than four dimensions. In fact, the subject reached a certain degree of maturity and since most of the contributors played a major role in that progress, this volume constitutes a definitive treatise on this subject. Some of the subjects dealt with include: Quantum Groups and their Representations; W-Algebras and their Role in Physical Systems; Conformally Invariant Quantum Field Theories; Integrable Systems; Topological Field Theories.

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Contents: Conformal Boundary Conditions OCo and What They Teach Us (V B Petkova & J-B Zuber); A Physical Basis for the Entropy of the AdS 3 Black Hole (S Fernando & F Mansouri); Spinon Formulation of the Kondo Problem (A Klmper & J R Reyes-Martinez); Boundary Integrable Quantum Field Theories (P Dorey); Finite Size Effects in Integrable Quantum Field Theories (F Ravanini); Nonperturbative Analysis of the Two-Frequency Sine-Gordon Model (Z Bajnok et al.); Screening in Hot SU(2) Gauge Theory and Propagators in 3D Adjoint Higgs Model (A Cucchieri et al.); Effective Average Action in Statistical Physics and Quantum Field Theory (Ch Wetterich); Phase Transitions in Non-Hermitean Matrix Models and the OC Single RingOCO Theorem (J Feinberg et al.); Unraveling the Mystery of Flavor (A Falk); The Nahm Transformation on R 2 X T 2 (C Ford); A 2D Integrable Axion Model and Target Space Duality (P Forgics); Supersymmetric Ward Identities and Chiral Symmetry Breaking in SUSY QED (M L Walker); and other papers. Readership: Theoretical, mathematical and high energy physicists."

The contributions in this conference proceeding present an alternative approach to solving the Quantum Field Theory problem using the variational approach. Many different issues are visited using this approach — Yang Mills Theory, going beyond the Guassian Approximation, in QCD and QED.

During the past 15 years, quantum field theory and classical statistical mechanics have merged into a single field, and the need for nonperturbative methods for the description of critical phenomena in statistical mechanics as well as for problems in elementary particle physics are generally acknowledged. Such methods formed the central theme of the 1987 Cargese Advanced Study Institut. e on "Nonpert. urbat. ive Quantum Field Theory." The use of conformal symmet. ry has been of central interest in recent years, and was a main subject at. t. he ASI. Conformal invariant quantum field theory describes statistical mechanical systems exactly at a critical point, and can be analysed to a remarkable ext. ent. by group t. heoretical methods. Very strong results have been obtained for 2-dimensional systems. Conformal field theory is also the basis of string theory, which offers some hope of providing a unified t. heory of all interactions between elementary particles. Accordingly, a number of lectures and seminars were presented on these two topics. After syst. ematic introductory lectures, conformal field theory on Riemann surfaces, orbifolds, sigma models, and application of loop group theory and Grassmannians were discussed, and some ideas on modular geometry were presented. Other lectures combined' traditional techniques of constructive quant. um field theory with new methods such as the use of index-t. heorems and infinite dimensional (Kac Moody) symmetry groups. The problems encountered in a quantum mechanical description of black holes were discussed in detail.