A nonrelativistic nucleon-nucleon (NN) coupled channels isobar model is used to calculate nuclear medium corrections to the first-order Watson optical potential for nucleon-nucleus scattering. The NN interaction includes π, 2π, ρ, η, and ω exchange for the pure nucleonic sector, one-pion exchange for nucleon-isobar coupling, and phenomenological short-range interactions for both the diagonal and coupling terms. Good fits to NN elastic phase shifts from 0–1 GeV have been obtained with this model. The specific nuclear medium effects studied here include Pauli blocking of intermediate nucleon scattering states and off-shell binding energy shifts. On-momentum-shell matrix elements of the density dependent, effective NN t matrix are used to calculate the local proton-nucleus optical potential assuming the local density approximation. The model is applied to proton elastic scattering from ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$, ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$, and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ at 320, 400, 500, 650, and 800 MeV and the predictions are compared with available data. In general, the medium modifications significantly affect the nonrelativistic predictions, even at 800 MeV, and bring about a substantial, overall improvement in the description of differential cross section and spin observable data. The improvements occur for each case and at all angles studied, but the agreement is most successful for forward angle differential cross sections and for spin observable data from 1 to 3 ${\mathrm{fm}}^{\mathrm{-}1}$. Deficiencies remain in the density dependent, nonrelativistic predictions for the forward angle spin observables where relativistic models are quite successful. The relation of this work to other nonrelativistic models which include nuclear medium corrections, off-shell effects, and full-folding contributions is also discussed.

• Received 25 October 1989

DOI:https://doi.org/10.1103/PhysRevC.41.2816