Electric dipole polarizability in neutron-rich Sn isotopes as a probe of nuclear isovector properties

Abstract

The determination of nuclear symmetry energy, and in particular, its density dependence, is a long-standing problem for nuclear physics community. Previous studies have found that the product of electric dipole polarizability α D and symmetry energy at saturation density J has a strong linear correlation with L, the slope parameter of symmetry energy. However, current uncertainty of J hinders the precise constraint on L. We investigate the correlations between electric dipole polarizability α D (or times symmetry energy at saturation density J) in Sn isotopes and the slope parameter of symmetry energy L using the quasiparticle random-phase approximation based on Skyrme Hartree-Fock-Bogoliubov. A strong and model-independent linear correlation between α D and L is found in neutron-rich Sn isotopes where pygmy dipole resonance (PDR) gives a considerable contribution to α D , attributed to the pairing correlations playing important roles through PDR. This newly discovered linear correlation would help one to constrain L and neutron-skin thickness ∆R np stiffly if α D is measured with high resolution in neutron-rich nuclei. Besides, a linear correlation between α D J in a nucleus around β-stability line and α D in a neutron-rich nucleus can be used to assess α D in neutron-rich nuclei.