Sensitivity of nucleon-nucleus scattering to the off-shell behavior of on-shell equivalent NN potentials.

The sensitivity of nucleon-nucleus elastic scattering to the off-shell behavior of realistic nucleon-nucleon interactions is investigated when on-shell equivalent nucleon-nucleon potentials are used. The study is based on applications of the full-folding optical model potential for an explicit treatment of the off-shell behavior of the nucleon-nucleon effective interaction. Applications were made at beam energies between 40 and 500 MeV for proton scattering from $^{40}\mathrm{Ca}$ and $^{208}\mathrm{Pb}$. We use the momentum-dependent Paris potential and its local on-shell equivalent as obtained with the Gelfand-Levitan and Marchenko inversion formalism for the two nucleon Schr\"odinger equation. Full-folding calculations for nucleon-nucleus scattering show moderate fluctuations in the corresponding observables. This sets narrow margins within which off-shell features of the nucleon-nucleon interaction can be resolved. Based on these results, inversion potentials were also constructed directly from phenomenological phase shifts (SM94). Their use in nucleon-nucleus scattering at intermediate energies provides an improved description of the data relative to those obtained from current realistic potential models. \textcopyright{} 1996 The American Physical Society.