In August 1982 a group of 104 physicists from 70 laboratories of 31 countries met in Erice to attend the 20th Course of the Inter national School of Subnuclear Physics. The countries represented at the School were: Argentina, Australia, Austria, Belgium, Brazil, Bulgaria, Canada, Chile, China, Czechoslovakia, France, the Federal Republic of Germany, Greece, India, Iran, Israel, Italy, Japan, Morocco, the Netherlands, Norway, Poland, South Africa, Spain, Sweden, Switzerland, Turkey, the United Kingdom, the United States of America, Yugoslavia, and Zimbabwe. The School was sponsored by the Italian Ministry of Public Education (MPI), the Italian Ministry of Scientific and Techno- logical Research (MRSI), the Sicilian Regional Government, and the Weizmann Institute of Science. This year, on the occasion of the 60th birthday of Chen Ning Yang, the "Ettore Majorana" Centre decided to pay tribute to the outstanding scientific achievements of one of the most prominent scientists of our time, by dedicating the 20th Course of the International School of Subnuclear Physics to a review of the pre sent status of one of the fields of physics where Chen Ning Yang has contributed most profoundly: gauge interactions. The theo retical foundations and the most recent developments were presented by Chen Ning Yang. The most general consequences of a gauge inter action -- supersymmetry -- with its theoretical aspects and the experimental implications were discussed by Sergio Ferrara and Demetrios Nanopoulos."

There have been many demonstrations, particularly for magnetic impurity ions in crystals, that spin-Hamiltonians are able to account for a wide range of experimental results in terms of much smaller numbers of parameters. Yet they were originally derived from crystal field theory, which contains a logical flaw; electrons on the magnetic ions are distinguished from those on the ligands. Thus there is a challenge: to replace crystal field theory with one of equal or greater predictive power that is based on a surer footing. The theory developed in this book begins with a generic Hamiltonian, one that is common to most molecular and solid state problems and that does not violate the symmetry requirements imposed on electrons and nuclei. Using a version of degenerate perturbation theory due to Bloch and the introduction of Wannier functions, projection operators, and unitary transformations, Stevens shows that it is possible to replace crystal field theory as a basis for the spin-Hamiltonians of single magnetic ions and pairs and lattices of magnetic ions, even when the nuclei have vibrational motion.

The power of the method is further demonstrated by showing that it can be extended to include lattice vibration and conduction by electron hopping such as probably occurs in high-Tc superconductors. Thus Stevens shows how an apparently successful ad hoc method of the past can be replaced by a much more soundly based one that not only incorporates all the previous successes but appears to open the way to extensions far outside the scope of the previously available methods. So far only some of these have been explored. The book should therefore be of great interest to all physicists and chemists concerned with understanding the special properties of molecules and solids that are imposed by the presence of magnetic ions.

Originally published in 1997.

The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These paperback editions preserve the original texts of these important books while presenting them in durable paperback editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.

On the occasion of the 50th anniversary of the journal Theoretical Chemistry Accounts, leading researchers in theoretical chemistry present current and forward-looking perspectives on major developments in the field. Originally published in the journal, these outstanding contributions are now available in a hardcover print format. This collection will be of benefit in particular to those research groups and libraries that have chosen to have only electronic access to the journal.

With contributions from Christopher J. Cramer, Gino A. DiLabio, Filipp Furche, Sophya Garashchuk, Peter M.W. Gill, Hua Guo, So Hirata, Brian K. Kendrick, Hans Lischka, Wenjian Liu, Fernando R. Ornellas, Irina Paci, Kirk A. Peterson, Markus Reiher, Jeffrey R. Reimers, Manuel Smeu, Seiichiro Ten-no, Diego Troya, Donald G. Truhlar, Christoph van Wullen, Dong H. Zhang

"

CP violation is an intriguing and elusive subject, and current knowledge of it remains limited, on both the experimental and theoretical levels. Researchers lack a fundamental understanding of its origin, and this is all the more important because CP violation is related to the generation problem and mass problem, two of the basic open questions in particle physics. This book provides beginning researchers with a self-contained introduction to the subject, starting at an elementary level and taking the reader to the forefront of current research.

This is a 1958 study of the scattering of particles which occurs when atomic nuclei collide. It provides one of the main lines of attack in exploring the forces within the nuclei themselves. Using the particle accelerators which were then available, the authors design experiments in which the less complex particles collide under controlled conditions, yielding quantitative data from which information about nuclear forces can be deduced. This book describes the physics of nuclear scattering, including the experimental results and their interpretation in terms of nuclear forces and nuclear structure. On the experimental side, standard equipment has been discussed only in the special context of scattering technique. The theoretical discussion assumes a general acquaintance with quantum mechanics and with elementary scattering formulae encountered elsewhere in relation to the scattering of electrons by atoms.

Before you lies the proceedings oft he NATO Advanced Study Institute/Newton Institute Workshop "Confinement, duality and non perturbative aspects of QCD." The school covered the most important techniques to study Quantum Chromodynamics (QCD) andconfinement, fromlattice gauge theory, through Wilson's renormalisation group, to electromagnetic duality. The organisingcommittee existed of: Ian Drummond (DAMTP, Cambridge), Mikhail Shifman (Minneapolis), Peter West (King's, London), and Pierrevan Baal (Leiden), who acted as director oft he school. This summer school was the concluding activity ofa six month programme on "Non perturbative Aspects of Qua ntum Field Theory" taking place at the Isaac Newton Institute for Mathematical Sciences in Ca mbridge, UK, whic h started in January 1997, organised by David Olive, Pierre van Baal, and Peter West. A large number ofthe lecturers also participated in the programme and a few programme participants were asked to present a seminar at the school. Not contained in these proceedings are the seminars by Peter Landshoff (DAMTP, Cambridge) on "The Pomeron" and Ludwig Faddeev (Steklov Math. Inst., St. Petersburg) on "Knot like solitons in 3+1 dimen sional field theory." In additiont o the lectures and seminars there were two poster sessions at which participants presented their work. Authors and titles ofthese posters are listed on a separate page. These pro ceedings address the longstanding question of understanding how quarks are confined w ithin subnuclear particles.

This volume contains two major articles, one providing a historical retrosp- tive of one of the great triumphs of nuclear physics in the twentieth century and the other providing a didactic introduction to one of the quantitative tools for understanding strong interactions in the twenty-first century. The article by Igal Talmi on "Fifty Years of the Shell Model - the Quest for the Effective Interaction", pertains to a model that has dominated nuclear physics since its infancy and that developed with astonishing results over the next five decades. Talmi is uniquely positioned to trace the history of the Shell Model. He was active in developing the ideas at the shell model's inception, he has been central in most of the subsequent initiatives which expanded, cl- ified and applied the shell model and he has remained active in the field to the present time. Wisely, he has chosen to restrict his review to the domin- ing issue: the choice of the effective interactions among valence nucleons that determine the properties of low lying nuclear energy levels. The treatment of the subject is both bold and novel for our series. The ideas pertaining to the effective interaction for the shell model are elucidated in a historical sequence.

vii FOREWORD TO THE ENGLISH EDITION The lectures which I gave at the University of Chicago ix It is an unusual pleasure to present Professor Heisen- in the spring of 1929 afforded me the opportunity of re- berg's Chicago lectures on "The Physical Principles of viewing the fundamental principles of quantum theory. the Quantum Theory" to a wider audience than could Since the conclusive studies of Bohr in 1927 there have attend them when they were originally delivered. Pro- been no essential changes in these principles, and many fessor Heisenberg's leading place in the development of new experiments have confirmed important consequences the new quantum mechanics is well recognized by those of the theory (for example, the Raman effect). But even who have been following its growth. It was in fact he who today the physicist more often has a kind of faith in the first saw clearly that in the older forms of quantum theory we were describing our spectra in terms of atomic mecha- correctness of the new principles than a clear understa- nisms regarding which we could gain no definite knowl- ing of them. For this reason the publication of these C- cago lectures in the form of a small book seems justified. edge, anq who first found a way to interpret (or at least describe) spectroscopic phenomena without assuming Since the formal mathematical apparatus of the quan- the existence of such atomic mechanisms.

By providing the reader with a foundational background in high spin nuclear structure physics and exploring exciting current discoveries in the field, this book presents new phenomena in a clear and compelling way. The quest for achieving the highest spin states has resulted in some remarkable successes which this monograph will address in comprehensive detail. The text covers an array of pertinent subject matter, including the rotational alignment and bandcrossings, magnetic rotation, triaxial strong deformation and wobbling motion and chirality in nuclei. This book offers a clearly-written and up-to-date treatment of the topics covered. The prerequisites for a proper appreciation are courses in nuclear physics and nuclear models and measurement techniques of observables like gamma-ray energies, intensities, multi-fold coincidences, angular correlations or distributions, linear polarization, internal conversion coefficients, short lifetime (pico-second range) of excited states etc. and instrumentation and data analysis methods.

Principles and Applications of ESR Spectroscopy fills the gap between the detailed monographs in ESR spectroscopy and the general textbooks in molecular physics, physical chemistry, biochemistry or spectroscopy. The latter only briefly explain the underlying theory and do not provide details about applications, while the currently available ESR textbooks are primarily focused on the technique as such. This text is based upon the authors' long experience of teaching the subject to a mixed audience, in the extreme case ranging from physics to biology. The potential of the method is illustrated with applications in fields such as molecular science, catalysis and environmental sciences, polymer and materials sciences, biochemistry and radiation chemistry/physics. Theoretical derivations have in general been omitted, as they have been presented repeatedly in previous works. The necessary theory is instead illustrated by practical examples from the literature.

This is a comprehensive overview of the information yielded by electroweak probes about the nuclear- and subnuclear-scale structure of matter. Lepton-induced processes from low energy through to the highest energies are considered. The first three lectures review electromagneticprocesses in hadrons; others cover the properties of partons, the behaviour of the constituents of the hadron, muon and neutrino scattering etc. An introduction to electroweak theory including the status of precision tests and data analyses is given along with a report on the first results from HERA. The lecturers have endeavoured to achieve a balance between scientific and didactic aspects thus making the book accessible also to students of nuclear and particle physics.

In this text the author gives a rather complete account of the available experimental information on neutral current reactions as predicted by the standard theory of electroweak interactions. The data, which range from atomic parity violation to the discovery of the W and Z bosons, impressively support the theory as formulated by Glashow, Weinberg and Salam. The experimental data are critically reviewed and related to the standard theory, whose formal essentials are presented in a transparent way. A complete compilation is given of precision measurements of the Weinberg angle. Special attention is paid to high energy electron-positron experiments at PEP and PETRA leading to the most precise value of the Weinberg angle so far made from such experiments. Latest results from the high-statistics deep-inelastic neutrino scattering experiments have been included along with recent measurements of neutrino electron scattering, data and analysis for polarized-electron nucleon scattering, polarized-muon scattering, atomic parity violation and proton-antiproton experiments establishing the nature of the intermediate bosons.

The three articles of the present volume pertain to very different subjects, all ofconsiderable current interest. The first reviews the fascinating history ofthe search for nucleon substructure in the nucleus using the strength ofGamow- Teller excitations. The second deals with deep inelastic lepton scattering as a probe ofthe non-perturbative structure of the nucleon. The third describes the present state ofaffairs for muon catalyzed fusion, an application of nuclear physics which many new experiments have helped to elucidate. This volume certainly illustrates the broad range ofphysics within our field. The article on Nucleon Charge-Exchange Reactions at Intermediate Energy, by Parker Alford and Brian Spicer, reviews recent data which has clarified one of the greatest puzzles of nuclear physics during the past two decades, namely, the "missing strength" in Gamow-Teller (GT) transitions. The nucleon-nucleon interaction contains a GT component which has a low-lying giant resonance. The integrated GT strength is subject to a GT sum rule. Early experiments with (n, p) charge exchange reactions found only about half of the strength, required by the sum rule, in the vicinity of the giant resonance. At the time, new theoretical ideas suggested that the GT strength was especially sensitive to renormalization from effects pertaining to nucleon substructure, particularly the delta excitation of the nucleon in the nucleus.

The XII Max Born Symposium has a special character. It was held in honour th of Jan Lopusza nski on the occasion of his 75 birthday. As a rule the Max Born Symposia organized by the Institute of Theoretical Physics at the University of Wroc law were devoted to well-de ned subjects of contemporary interest. This time, however, the organizers decided to make an exception. Lopusza nski's in?uence on and contribution to the development of th- retical physics at Wrocla w University is highly appreciable. His personality and scienti c achievements gave him authority which he used to the best - vantage of the Institute. In fact we still pro t from his knowledge, experience and judgment. Lopusza nski's scienti c activity extended over about half a century. He successfully participated in research on the most important and fascinating issues of theoretical physics. During his scienti c career he met and made friends with many outstanding physicists who shaped theoretical physics to the present form. For this reason, as well as the coincidence of the approaching end of the century, we thought that it would be interesting and instructive to give the symposium a retrospective character. We decided to trust the speakers' judgment and intuition for the choice of subjects for their talks. We just asked them to give the audience the important message based on their knowledge and experience.

During July-August 1989. a group of 75 physicists from 52 laboratories in 16 countries met in Erice for the 27th Course of the International School of Subnuclear Physics. The countries represented were: Austria. Bulgaria. Canada. China. Denmark. France. the Federal Republic of Germany. Hungary. India. Italy. Pakistan. Poland. Switzerland. United Kingdom. and the Union of the Soviet Socialist Republics and the United States of America. The School was sponsored by the European Physical Society (EPS). the Italian Ministry of Education (MPI). the Italian Ministry of Scientific and Technological Research (MRST). the Sicilian Regional Government (ERS). and the Weizmann Institute of Science. In addition to some crucial problems in the Superworld Theory. developed by S. Ferrara and L. Hall. the School was focused on the most advanced topics which have attracted our attention during the last year. These are of a phenomenological nature: the problem of the spin inside the proton (G. Altarelli). some crucial QCD tests (R. Baldini-Celio and S. Brodsky). the jet phenomenology as predicted by QCD (Y. Dokshitzer); and of basic (therefore by far more difficult to solve) value. such as the understanding of the fundamental constants of Nature (G. Veneziano) and the new ideas on the cosmological constant (A. Stominger and G. Veneziano).

After the development of the tunable laser, experimental studies in Rydberg states of atoms and molecules grew at a remarkable rate. Fundamental questions were resolved, opening doors for more experimental activity and theoretical inquiry. In this comprehensive summary of knowledge of Rydberg states, which was originally published in 1983, Professors Stebbings and Dunning brought together a select collection of experimental and theoretical discussions. Composed of works by the acknowledged leaders in the field, this volume will be of value for anyone with an interest in molecular physics.

The knowledge of the interactions of photons with hadrons has considerably improved with the study of high-energy lepton-proton collisions at HERA. The results on the partonic interactions of photons are summarized in comparison with photon-nucleon, two-photon, and proton-antiproton experiments.

These proceedings give fundamental information on the collision mechanisms of ions and atoms at relatively high energies and on their highly excited atomic states. The information derived from such studies can often be applied in other fields such as material analysis, dosimetry, the study of the upper atmosphere and controlled fusion. Phenomena involving the classical ion-atom collision fields, impact parameter dependences, quasimolecular and electron correlation effects, coherence phenomena, the electron and photon spectroscopy of highly charged projectile and recoil ions, the loss and capture of electrons, molecular and solid state effects, and different aspects of instrumentation are all discussed in this volume.

The investigation ofmost problems of quantum physics leads to the solution of the Schrodinger equation with an appropriate interaction Hamiltonian or potential. However, the exact solutions are known for rather a restricted set of potentials, so that the standard eternal problem that faces us is to find the best effective approximation to the exact solution of the Schrodinger equation under consideration. In the most general form, this problem can be formulated as follows. Let a total Hamiltonian H describing a relativistic (quantum field theory) or a nonrelativistic (quantum mechanics) system be given. Our problem is to solve the Schrodinger equation Hlft = Enlftn, n i. e., to find the energy spectrum {En} and the proper wave functions {lft } n including the'ground state or vacuum lft = 10). The main idea of any ap o proximation technique is to find a decomposition in such a way that Ha describes our physical system in the "closest to H" manner, and the Schrodinger equation HolJt. (O) = E(O)lJt. (O) n n n can be solved exactly. The interaction Hamiltonian HI is supposed to give small corrections to the zero approximation which can be calculated. In this book, we shall consider the problem of a strong coupling regime in quantum field theory, calculations ofpath or functional integrals over the Gaussian measure and spectral problems in quantum mechanics. Let us con sider these problems briefly."

Gauge field theories underlie all models now used in elementary particle physics. These theories refer to the class of singular theories which are also theories with constraints. The quantization of singular theories remains one of the key problems of quantum field theory and is being intensively discussed in the literature. This book is an attempt to fill the need for a comprehensive analysis of this problem, which has not heretofore been met by the available monographs and reviews. The main topics are canonical quantization and the path integral method. In addition, the Lagrangian BRST quantization is completely described, for the first time in a monograph. The book also presents a number of original results obtained by the authors, in particular, a complete description of the physical sector of an arbitrary gauge theory, quantization of singular theories with higher theories with time-dependent constraints, and correct derivatives, quantization of canonical quantization of theories of a relativistic point-like particle. As a general illustration we present quantization of field theories such as electrodynamics, Yang-Mills theory, and gravity. It should be noted that this monograph is aimed not only at giving the reader the rules of quantization according to the principle "if you do it this way, it will be good," but also at presenting strong arguments based on the modem interpretation of the classical and quantum theories which show that these methods. are the natural, if not the only possible ones."

243 number n and orbital angular momentum 1, but also a total angular momentum 1 f = 1 +/- !. This modification lead to striking successes for the model. Almost without exception, the ground state spins of odd nuclei were found to be cor rectly predicted. Furthermore several other features of nuclei such as the occur rence of isomeric states and the values of magnetic dipole moments were explained, at least qualitatively. However the model completely failed to explain the large values of observed electric quadrupole moments and certain regularities in nuclear spectra, especially of rare earth nuclei. 4. 1950-1953. The emphatic success of the shell-model modified by a spin orbit force gave the necessary confidence and incentive to physicists to apply the model in detail to individual nuclei. Guided by parallel calculations in atomic spectroscopy, considerable effort was devoted to computing spectra of levels of nuclear systems with the so-called "Intermediate Coupling Model" in which the independent particle motion is considered to be perturbed by central particle particle interactions and spin-orbit forces. Computational labour restricts such calculations to nuclei near closed shells, say within four particles or holes of closed shells. This explains why only light nuclei (A < 20) and isolated groups of nuclei higher in the Periodic Table were thus treated. Usually such calculations were rewarded by agreement with experiment especially those for light nuclei 2 and 20S nuclei near the double closed shell at Pb 3.

This book is the result of a graduate-level "special topics" course I gave at the University of Rochester in 1970. The purpose of the course was to discuss as far as possible all known symmetries in nuclei, with special emphasis on dynamical symmetries. Since there was no comprehensive account of this subject in the literature, I was encouraged to write a review based on my lecture notes. The end result is the present volume. Like the course, the book is intended mainly for graduate students and research workers in nuclear physics. The only prior knowledge required to follow the book is graduate-level quantum mechanics and nuclear physics and hence I believe that it can be useful to both experimental and theoretical nuclear physicists. In addition, the book should prepare a student to read the latest literature on the subject and also train him to do group theoretic work in nuclear physics. The organization of the material in the book is described in Chapter 1.

Infrared spectroscopy is a new and innovative technology to study protein folding/misfolding events in the broad arsenal of techniques conventionally used in this field. The progress in understanding protein folding and misfolding is primarily due to the development of biophysical methods which permit to probe conformational changes with high kinetic and structural resolution. The most commonly used approaches rely on rapid mixing methods to initiate the folding event via a sudden change in solvent conditions. Traditionally, techniques such as fluorescence, circular dichroism or visible absorption are applied to probe the process. In contrast to these techniques, infrared spectroscopy came into play only very recently, and the progress made in this field up to date which now permits to probe folding events over the time scale from picoseconds to minutes has not yet been discussed in a book. The aim of this book is to provide an overview of the developments as seen by some of the main contributors to the field. The chapters are not intended to give exhaustive reviews of the literature but, instead to illustrate examples demonstrating the sort of information, which infrared techniques can provide and how this information can be extracted from the experimental data. By discussing the strengths and limitations of the infrared approaches for the investigation of folding and misfolding mechanisms this book helps the reader to evaluate whether a particular system is appropriate for studies by infrared spectroscopy and which specific advantages the techniques offer to solve specific problems.

Written in a pedagogical way, the articles in this book address graduate students as well as researchers and are well suited for seminar work. Subjects at the forefront of nuclear research, bordering other areas of many-particle physics, such as electron scattering at different energy scales, new physics with radioactive beams, multifragmentation, relativistic nuclear physics, high spin nuclear problems, chaos, the role of the continuum in nuclear physics or recent calculations with the shell model are presented. It is felt that the topics treated in this book address the main future lines of development of nuclear physics.

In these days of specialization it is important to bring together physicists working in diverse areas to exchange and share their ideas and excitement. This leads to cross-fertilization of ideas, and it enriches, as in biological systems, a specialized field with new strength, development and direction derived from another area. Although this might be an uncommon thing, it is an important step in our under standing of the physical world around us, which is, after aIl, the main purpose of physics. The seed for this conference was really sowed when one of us (MB) and Mr. Manngard showed some a-scattering data at backward angles to FBM one summer about four years ago. That occasion led to a long research collaboration between the Abo Akademi physicists and other scientists in several countries. The actual idea to explore the possibility of holding a conference, however, crystallized in the summer of 1989 during a visit of FBM to Abo Akademi. The final decision to organize a conference was made after MB visited Profes sor Ben Mottelson in Copenhagen and Professor Anagnostatos in Athens. At this point it was recognized that there are similarities as weIl as differences between clustering phenomena in nuclei and systems consisting of atoms. It was therefore conjectured that it could be very stimulating to bring together these groups to exchange their ideas and to leam from each other's fields. A conference along these lines, we hoped, would contribute to an increased mutual understanding."