In recent years there has been growing interest in the nucleon-nucleon correl­ ations inside nuclei. In many respects the motions of the nucleons can be very well described by an overall mean field, so that the motion of each nucleon is governed by the mean field due to all the other nucleons. This concept underlies the Fermi-gas, Hartree-Fock and shell models and has enabled a range of nuclear properties to be calculated, often to surprising accuracy. It gradually became clear, however, that these mean-field models are limited by the effects due to the very strong interactions between the nucleons that occur at short distances; these are the short-range correlations. They are responsible for instance for the high-momentum components in the nucleon momentum dis­ tribution, and prevent the simultaneous description of the nuclear density and momentum distributions by the same mean field. It thus becomes necessary to develop methods for including the effects of nucleon correlations in nuclei, and these are the main subject of this book. Some related problems of nuclear structure were discussed in an earlier book by the same authors: Nucleon Momentum and Density Distributions in Nuclei (Clarendon Press, Oxford, 1988). The main aim of that book was to study the effects of nucleon-nucleon correlations, both short-range and tensor, on the nucleon momentum distribution, which is particularly sensitive to these correl­ ations, and on the nucleon density distribution.

1 Mean-field and Beyond Mean-field Nuclear Theoretical Methods.- 1 Independent-particle Models.- 1.1 The Fermi-gas Model.- 1.2 The Shell Model.- 1.3 The Hartree-Fock Approximation.- 2 Complex Mean-field Analyses.- 2.1 The Complex Potential. Formal Considerations.- 2.2 The Complex Potential for Bound and Scattering States.- 2.3 Dispersion Relations Methods.- 3 Basic Correlation Methods.- 3.1 An Analysis of Mean-field Theories.- 3.2 Correlation Methods Related to Mass Operator Expansions.- 3.3 Beyond Single Slater Determinant Methods.- 4 Further Correlation Methods.- 4.1 The Generator Coordinate Method.- 4.2 The Coherent Density Fluctuation Model.- 4.3 The Natural Orbital Method.- 2 Nucleon Correlations and Nuclear Structure.- 5 Spectral Functions.- 5.1 Introduction.- 5.2 Green Function Description of the Spectral Function.- 5.3 Spectral Functions within the Coherent Density Fluctuation Model.- 5.4 Sum Rules for the Spectral Function.- 6 Natural Orbitals and Occupation Numbers in Nuclei.- 6.1 Nucleon Correlations and Single-particle Occupation Numbers.- 6.2 Applications of the Natural Orbital Method.- 6.3 The Natural Orbital Representation within the Coherent Density Fluctuation Model (CDFM).- 6.4 The Natural Orbital Representation within the Generator Coordinate Method (GCM).- 6.5 Comparison of CDFM and GCM Results with ExperimentaData for Occupation Numbers.- 7 Momentum Distributions in Nuclei.- 7.1 Nucleon Momentum and Density Distributions.- 7.2 Cluster Momentum Distributions in Nuclei.- 8 Ground and Excited Collective Nuclear States within the Coherent Density Fluctuation Model and the Generator Coordinate Method.- 8.1 Energies and Density Distributions in Ground and Excited Monopole States within the Coherent Density Fluctuation Model.- 8.2 Generator Coordinate Method Calculations of Energies and the Density Distributions of the Ground and Excited Monopole States.- 3 Nucleon Correlations and Nuclear Reactions.- 9 Electron-nucleus Scattering.- 9.1 Electron Elastic Scattering.- 9.2 Quasielastic Electron Scattering.- 9.3 Deep-inelastic Lepton-nucleus Scattering.- 10 Photonuclear Reactions at Intermediate Energies.- 11 Intermediate Energy Proton-nucleus Scattering.- 11.1 Proton-nucleus Scattering and Nucleon Correlations.- 11.2 Elastic Proton-nucleus Scattering within the Coherent Density Fluctuation Model.- 11.3 Deep-inelastic Proton-nucleus Scattering within the Coherent Density Fluctuation Model.- 12 Elastic Scattering of Complex Nuclear Systems.- 12.1 Intermediate-energy Alpha-particle Elastic Scattering on Nuclei.- 12.2 Heavy-ion Elastic Scattering.- References.- Author Index.