DENSITY-DEPENDENT (P)OVER-BAR-NUCLEUS OPTICAL POTENTIALS FROM GLOBAL FITS TO (P)OVER-BAR ATOM DATA

Zero kinetic energy (p) over bar-nucleus optical potentials are studied phenomenologically by fitting to a comprehensive set of atomic data across the periodic table. Density dependence is introduced into the isoscalar s-wave component of V-opt and several families of density-dependent (DD) isoscalar optical-potential solutions are found, offering improved fits over those for a density independent parameterization. DD solutions which respect the low-density limit V-opt --> t((p) over bar N)rho(r), with or without a p-wave term constrained by (N) over bar N potential models, provide good fits to the (p) over bar atom data, but somewhat inferior to the best-fit density independent parameterizations. It is also found that the isovector components of V-opt are poorly determined in global fits, exhibiting a strong sensitivity to the neutron excess densities employed, particularly in the far nuclear surface region. This sensitivity is used to update the derivation of the isovector s-wave parameters from data on the isotope sequences O-16-O-18 and Mo-92-Mo-98.