Charge exchange spin-dipole excitations in 90Zr and 208Pb and the neutron matter equation of state

Charge exchange spin-dipole (SD) excitations in Zr-90 and Pb-208 are studied by using a Skyrme Hartree-Fock + random phase approximation. The calculated spin-dipole strength distributions are compared with experimental data obtained by Zr-90(p,n)Nb-90 and Zr-90(n,p)Nb-90 reactions. The model-independent SD sum rule values of various Skyrme interactions are studied in comparison with the experimental values to determine the neutron skin thickness of Zr-90. The pressure of the neutron matter equation of state and the nuclear matter symmetry energy are discussed in terms of the neutron skin thickness and peak energies of SD strength distributions.