Folding model study of the charge-exchange scattering to the isobaric analog state and implication for the nuclear symmetry energy (original) (raw)

2014, The European Physical Journal A

The Fermi transition (∆L = ∆S = 0 and ∆T = 1) between the nuclear isobaric analog states (IAS), induced by the chargeexchange (p, n) or ( 3 He,t) reaction, can be considered as "elastic" scattering of proton or 3 He by the isovector term of the optical potential (OP) that flips the projectile isospin. The accurately measured (p, n) or ( 3 He,t) scattering cross-section to the IAS can be used, therefore, to probe the isospin dependence of the proton or 3 He optical potential. Within the folding model, the isovector part of the OP is determined exclusively by the neutron-proton difference in the nuclear densities and the isospin dependence of the effective nucleon-nucleon (NN) interaction. Because the isovector coupling explicitly links the isovector part of the proton or 3 He optical potential to the cross section of the charge-exchange (p, n) or ( 3 He,t) scattering to the IAS, the isospin dependence of the effective (in-medium) NN interaction can be well tested in the folding model analysis of these charge-exchange reactions. On the other hand, the same isospin-and density dependent NN interaction can also be used in a Hartree-Fock calculation of asymmetric nuclear matter, to estimate the nuclear matter energy and its asymmetry part (the nuclear symmetry energy). As a result, the fine-tuning of the isospin dependence of the effective NN interaction against the measured (p, n) or ( 3 He,t) cross sections should allow us to make some realistic prediction of the nuclear symmetry energy and its density dependence.