Recent Progress in Many-Body Theories

The present volume contains the texts of the invited talks delivered at the Fifth International Conference on Recent Progress in Many-Body Theories held in Oulu, Finland during the period 3-8 August 1987. The general format and style of the meeting followed closely those which had evolved from the earlier conferences in the series: Trieste 1978, Oaxtepec 1981, Altenberg 1983 and San Francisco 1985. Thus, the conferences in this series are in tended, as far as is practicable, to cover in a broad and balanced fashion both the entire spectrum of theoretical tools developed to tackle the quan tum many-body problem, and their major fields of* application. One of the major aims of the series is to foster the exchange of ideas and techniques among physicists working in such diverse areas of application of many-body theories as nucleon-nucleon interactions, nuclear physics, astronomy, atomic and molecular physics, quantum chemistry, quantum fluids and plasmas, and solid-state and condensed matter physics. A special feature of the present meeting however was that particular attention was paid in the programme to such topics of current interest in solid-state physics as high-temperature superconductors, heavy fermions, the quantum Hall effect, and disorder. A panel discussion was also organised during the conference, under the chair manship of N. W. Ashcroft, to consider the latest developments in the extreme ly rapidly growing field of high-T superconductors.