Folding model study of the isobaric analog excitation: Isovector density dependence, Lane potential, and nuclear symmetry energy

A consistent folding model analysis of the (Delta S=0,Delta T=1) charge exchange (p,n) reaction measured with Ca-48, Zr-90, Sn-120, and Pb-208 targets at the proton energies of 35 and 45 MeV is done within a two-channel coupling formalism. The nuclear ground state densities given by the Hartree-Fock-Bogoliubov formalism and the density-dependent CDM3Y6 interaction were used as inputs for the folding calculation of the nucleon optical potential and (p,n) form factor. To have an accurate isospin dependence of the interaction, a complex isovector density dependence of the CDM3Y6 interaction has been carefully calibrated against the microscopic Brueckner-Hartree-Fock calculation by Jeukenne, Lejeune, and Mahaux before being used as folding input. Since the isovector coupling was used to explicitly link the isovector part of the nucleon optical potential to the cross section of the (p,n) reaction exciting the 0(+) isobaric analog states in Sc-48, Nb-90, Sb-120, and Bi-208, the newly parametrized isovector density dependence could be well tested in the folding model analysis of the (p,n) reaction. The isospin- and density-dependent CDM3Y6 interaction was further used in the Hartree-Fock calculation of asymmetric nuclear matter, and a realistic estimation of the nuclear symmetry energy was made.