The Quantum Mechanical Few Body Problem

Few-body systems are both technically relatively simple and physically non trivial enough to test theories quantitatively. For instance the He-atom played historically an important role in verifying predictions of QED. A similar role is contributed nowadays to the three-nucleon system as a testing ground far nuclear dynamics and maybe in the near future to few-quark systems. They are also often the basic building blocks for many-body systems like to some extent nuclei, where the real many-body aspect is not the dominant feature. The presentation of the subject given here is based on lectures held at var ious places in the last ten years. The selection of the topics is certainly subjec tive and influenced by my own research interests. The content of the book is simply organized according to the increasing nu mb er of particles treated. Be cause of its conceptual simplicity single particle motion is very suitable for in troducing the basic elements of scattering theory. Using these elements the two-body system is treated for the specific case of two nucleons, which is of great importance in the study of the nuclear interaction. Great space is devoted to the less trivial few-body system consisting of three particles. Again physical examples are taken solely from nuclear physics. Finally the four particle system is discussed so as to familiarize the reader with the techniques required for the formulations of n-bodies in general.

The quantum-mechanical few-body problem is of fundamental importance for all branches of microphysics and it has substantially broadened with the advent of modern computers. This book gives a simple, unified recipe to obtain precise solutions to virtually any few-body bound-state problem and presents its application to various problems in atomic, molecular, nuclear, subnuclear and solid state physics. The main ingredients of the methodology are a wave-function expansion in terms of correlated Gaussians and an optimization of the variational trial function by stochastic sampling. The book is written for physicists and, especially, for graduate students interested in quantum few-body physics.

The Quantum Mechanical Three-Body Problem deals with the three-body problem in quantum mechanics. Topics include the two- and three-particle problem, the Faddeev equations and their solution, separable potentials, and variational methods. This book has eight chapters; the first of which introduces the reader to the quantum mechanical three-body problem, its difficulties, and its importance in nuclear physics. Scattering experiments with three-particle breakup are presented. Attention then turns to some concepts of quantum mechanics, with emphasis on two-particle scattering and the Hamiltonian for three particles. The chapters that follow are devoted to the Faddeev equations, including those for scattering states and transition operators, and how such equations can be solved in practice. The solution of the Faddeev equations for separable potentials and local potentials is presented, along with the use of Padé approximation to solve the Faddeev equations. This book concludes with an appraisal of variational methods for bound states, elastic and rearrangement scattering, and the breakup reaction. A promising variational method for solving the Faddeev equations is described. This book will be of value to students interested in three-particle physics and to experimentalists who want to understand better how the theoretical data are derived.

Nuclear physics is undoubtedly a many-body problem. A nice introduction into the present status of this subject may be found in the comprehensive mono graph by P. Ring and P. Schuck "The Nuclear Many-Body Problem" (Springer, Berlin, Heidelberg, New York 1980). However, in view of the many challenging problems that remain to be tackled, it is sensible to consider systems with few particles as model cases. These provide the basis for solving the sophisticated many-body problem posed by intermediate and heavy nuclei. Out of the large number of existing nuclear systems, few-particle, that is few-nucleon, systems can be singled out to form a special group. This is possi ble because a comparatively small number of degrees of freedom (or dynamic variables) is required for a complete description of such systems. In these Lectures we utilize this to study few-body systems in great detail, in particular three-and four-body systems. In contrast to published monographs on the subject, we deal not just with nucleonic degrees of freedom but consider also non-nucleonic degrees of freedom. The range of approaches and methods examined exceeds the scope of other textbooks. The Lectures are organized in such a way as to guide the uninitiated reader through the essentials of solving the dynamical equations of few-body systems directly towards practical applications. Formally oriented readers might like to supplement their reading with texts such as "The Quantum Mechanical Few Body Problem" by W. GlOckle (Springer, Berlin, Heidelberg, New York 1983).

Nuclear physics is undoubtedly a many-body problem. A nice introduction into the present status of this subject may be found in the comprehensive mono graph by P. Ring and P. Schuck "The Nuclear Many-Body Problem" (Springer, Berlin, Heidelberg, New York 1980). However, in view of the many challenging problems that remain to be tackled, it is sensible to consider systems with few particles as model cases. These provide the basis for solving the sophisticated many-body problem posed by intermediate and heavy nuclei. Out of the large number of existing nuclear systems, few-particle, that is few-nucleon, systems can be singled out to form a special group. This is possi ble because a comparatively small number of degrees of freedom (or dynamic variables) is required for a complete description of such systems. In these Lectures we utilize this to study few-body systems in great detail, in particular three-and four-body systems. In contrast to published monographs on the subject, we deal not just with nucleonic degrees of freedom but consider also non-nucleonic degrees of freedom. The range of approaches and methods examined exceeds the scope of other textbooks. The Lectures are organized in such a way as to guide the uninitiated reader through the essentials of solving the dynamical equations of few-body systems directly towards practical applications. Formally oriented readers might like to supplement their reading with texts such as "The Quantum Mechanical Few Body Problem" by W. GlOckle (Springer, Berlin, Heidelberg, New York 1983).

The Asia-Pacific Conferences on Few-Body Problems in Physics tackle cover the various aspects of few-body systems in physics, with high caliber contributions from internationally renowned researchers. Readers will gain a clear picture of the latest developments in the field in both the theoretical and experimental sectors.The scope of these proceedings covers research in the following areas: three-body forces and few-nucleon dynamics, hadron structure and QCD; exotic hadrons and atoms; effective field theory in few-body physics; electromagnetic and weak processes in few-body systems; few-body dynamics in atoms, molecules, Bose-Einstein condensates and quantum dots; few-body approaches to unstable nuclei, nuclear astrophysics and nuclear clustering aspects; and hypernuclear physics.

Single-volume account of methods used in dealing with the many-body problem and the resulting physics. Single-particle approximations, second quantization, many-body perturbation theory, Fermi fluids, superconductivity, many-boson systems, more. Each chapter contains well-chosen problems. Only prerequisite is basic understanding of elementary quantum mechanics. 1967 edition.