Poul Henrik Damgaard – författare

Quantum field theory is one of most central constructions in 20th century th- retical physics, and it continues to develop rapidly in many different directions. The aim of the workshop “New Developments in Quantum Field Theory”, which was held in Zakopane, Poland, June 14-20, 1997, was to capture a broad selection of the most recent advances in this field. The conference was sponsored by the Scientific and - vironmental Affairs Division of NATO, as part of the Advanced Research Workshop series. This book contains the proceedings of that meeting. Major topics covered at the workshop include quantized theories of gravity, string theory, conformal field theory, cosmology, field theory approaches to critical phenomena and the renormalization group, matrix models, and field theory techniques applied to the theory of turbulence. One common theme at the conference was the use of large-Nmatrix models to obtain exact results in a variety of different disciplines. For example, it has been known for several years that by taking a suitable double-scaling limit, certain string theories (or two-dimensional quantum gravity coupled to matter) can be re-obtained from the large-Nexpansion of matrix models. There continues to be a large activity in this area of research, which was well reflected by talks given at our workshop. Remarkably, large- Nmatrix models have very recently – just a few months before our meeting – been shown to have yet another deep relation to string theory.

From August 21 through August 27, 1989 the Nato Advanced Research Workshop Probabilistic Methods in Quantum Field Theory and Quantum Gravity" was held at l'Institut d'Etudes Scientifiques, Cargese, France. This publication is the Proceedings of this workshop. The purpose of the workshop was to bring together a group of scientists who have been at the forefront of the development of probabilistic methods in Quantum Field Theory and Quantum Gravity. The original thought was to put emphasis on the introduction of stochastic processes in the understanding of Euclidean Quantum Field Theory, with also some discussion of recent progress in the field of stochastic numerical methods. During the final preparation of the meeting we broadened the scope to include all those Euclidean Quantum Field Theory descriptions that make direct reference to concepts from probability theory and statistical mechanics. Several of the main contributions centered around a more rigorous discussion of stochastic processes for the formulation of Euclidean Quantum Field Theory. These rather stringent mathematical approaches were contrasted with the more heuristic stochastic quantization scheme developed in 1981 by Parisi and Wu: Stochastic quan­ tization, its intrinsic BRST -structure and stochastic regularization appeared in many disguises and in connection with several different problems throughout the workshop.

Quantum field theory is one of most central constructions in 20th century th- retical physics, and it continues to develop rapidly in many different directions. The aim of the workshop “New Developments in Quantum Field Theory”, which was held in Zakopane, Poland, June 14-20, 1997, was to capture a broad selection of the most recent advances in this field. The conference was sponsored by the Scientific and - vironmental Affairs Division of NATO, as part of the Advanced Research Workshop series. This book contains the proceedings of that meeting. Major topics covered at the workshop include quantized theories of gravity, string theory, conformal field theory, cosmology, field theory approaches to critical phenomena and the renormalization group, matrix models, and field theory techniques applied to the theory of turbulence. One common theme at the conference was the use of large-Nmatrix models to obtain exact results in a variety of different disciplines. For example, it has been known for several years that by taking a suitable double-scaling limit, certain string theories (or two-dimensional quantum gravity coupled to matter) can be re-obtained from the large-Nexpansion of matrix models. There continues to be a large activity in this area of research, which was well reflected by talks given at our workshop. Remarkably, large- Nmatrix models have very recently – just a few months before our meeting – been shown to have yet another deep relation to string theory.

Already in 1997, the topics included in this meeting had been enlarged to include all different phases and phase transitions relevant on laboratory scales or in cosmology. The '98 meeting followed this trend, and there was a balanced combination of the physics associated with both strong and electroweak interactions (and beyond). The main motivation continues to be the understanding of the standard model in “extreme” situations, particularly relevant on the cosmological scale. Most contributions were in one way or another concerned with the finite-temperature aspects of strong and electroweak interactions, and, as in the previous meeting, one persistent theme was the present understanding of baryon-number asymmetry: how it can be created, and how it can be maintained beyond the earliest stages of the Universe. The recent progress in describing the real-time and nonequilibrium dynamics of the non-Abelian gauge was covered in a number of the main talks, as well as in several shorter contributions and posters. The conference presented examples of impressive analytical progress and equally impressive results from numerical simulations: the two techniques continue to fruitfully complement each other. One completely new theme at this conference was the recent suggestion that finite-density QCD may contain new and interesting condensed phases in the neighborhood of the conventional critical density separating quark matter from hadronic matter. All of these developments, and many more, are reflected in this book.