OPTICAL POTENTIALS NEAR FERMI-SURFACE BY NUCLEAR SCHWINGER-DYSON EQUATIONS WITH BARE VERTEX APPROXIMATION

Optical potentials near the Fermi surface are calculated using the bar e vertex nuclear Schwinger-Dyson method based on the sigma-omega model , malting use of results obtained on nuclear matter. Saturation and th e liquid-vapor instability of nuclear matter are discussed. Contributi ons of mesons affected by nuclear medium in the optical potentials are clarified: The omega-meson contribution is prominent and originates i n the difference between the transverse and longitudinal components of the omega-meson propagator. This difference vanishes without nuclear medium. As a result, the effective mass of nucleons increases rapidly near the Fermi energy, and the omega-meson dominance near the Fermi su rface in the imaginary potential agrees with the result in the non-rel ativistic Hartree-Fock calculation.