Low-energy E1 strength in select nuclei: Possible constraints on the neutron skins and the symmetry energy

TL;DR

This study investigates the relationship between low-energy E1 strength, neutron skin thickness, and symmetry energy in specific spherical neutron-rich nuclei using self-consistent RPA with Skyrme functionals, revealing strong correlations under certain conditions.

Contribution

It demonstrates that strong correlations exist between low-lying E1 strength, neutron skin, and symmetry energy in selected spherical neutron-rich nuclei, clarifying conditions for these relationships.

Findings

Strong correlation in spherical neutron-rich nuclei with low angular momentum orbitals.

Correlation between energy-weighted sum value and symmetry energy slope.

Deformation weakens the correlation.

Abstract

Correlations between low-lying electric dipole (E1) strength and neutron skin thickness are systematically investigated with the fully self-consistent random-phase approximation using the Skyrme energy functionals. The presence of strong correlation among these quantities is currently under dispute. We find that the strong correlation is present in properly selected nuclei, namely in spherical neutron-rich nuclei in the region where the neutron Fermi levels are located at orbits with low orbital angular momenta. The significant correlation between the fraction of the energy-weighted sum value and the slope of the symmetry energy is also observed. The deformation in the ground state seems to weaken the correlation.