Monte Carlo studies of momentum distributions and longitudinal response functions of A=3 and 4 nuclei

We review realistic nucleon-nucleon potentials and three-nucleon interaction models based on the two-pion exchange mechanism, describing their theoretical basis. The Faddeev method for the three-body nuclei, and variational approaches for the three-and four-body nuclei wave functions are used to represent the ground state of these nuclei. The variational method is discussed in some detail, and results for the binding energies and charge radii obtained with this method are reported. The Monte Carlo integration technique, also briefly reviewed, is used to evaluate various expectation values, and is generalized to calculate quantities such as momentum distributions and transition probabilities. The longitudinal structure function and the energy weighted sum of the longitudinal response are calculated in the few-body nuclei, and results obtained for these quantities in nuclear matter with chain summation techniques are also reported. The theoretical sum rules are then used to analyze most of the available experimental data on light, medium and heavy nuclei, extracted from inclusive (e,e') reactions. We then calculate the momentum distributions of protons in SHe, sH, and "He, and nucleon clusters, such as d+p in SHe and t+p and d+d in "He. The proton and d+p momentum distributions are compared with those extracted at Saclay from the plane-wave impulse approximation analysis of the exclusive reactions SHe(e,e'p)d and SHe(e,e'p)n+n. Lastly, the method of correlated basis functions (CBF) is generalized to describe the threenucleon and deuteron + nucleon continuum states. Correlated orthonormal (CO) wave functions for the continuum states are generated by orthogonalizing the CBF via a combination of Schmidt and Lowdin transformations, designed so that the CO states have correct energies. The longitudinal response of SHe and sH is calculated with the variational ground state wave function and the CO final states, and that of SHe is compared with the Saclay experimental data.U of I OnlyThesi