The p-40Ca and n-40Ca mean fields from the iterative moment approach

The real part V(r; E) of the p-40Ca and n-40Ca mean fields is extrapolated from positive towards negative energies by means of the iterative moment approach, which incorporates the dispersion relation between the real and imaginary parts of the mean field. The potential V(r; E) is the sum of a Hartree-Fock type component VHF(r; E) and a dispersive correction ΔV(r; E); the latter is due to the coupling of the nucleon to excitations of the 40Ca core. The potentials V(r; E) and VHF(r; E) are assumed to have Woods-Saxon shapes. The calculations are first carried out in the framework of the original version of the iterative moment approach, in which both the depth and the radius of the Hartree-Fock type contribution depend upon energy, while its diffuseness is constant and equal to that of V(r; E). The corresponding extrapolation towards negative energies is somewhat sensitive to the detailed parametrization of the energy dependence of the imaginary part of the mean field, which is the main input of the calculation. Moreover, the radius of the calculated Hartree-Fock type potential then increases with energy, in contrast to previous findings in 208Pb and 89Y. The absolute spectroscopic factors of low-lying single-particle excitations in 39Ca, 41Ca, 39K and 41Sc are found to be close to 0.8. (orig./HSI)