Abstract
We investigate the isoscalar and isovector response of neutron-rich nuclei, within a semiclassical transport model employing effective interactions for the nuclear mean field. In particular, we adopt the recently introduced SAMi-J Skyrme interactions, whose parameters are specifically tuned to improve the description of spin-isospin properties of nuclei. Our analysis evidences a relevant degree of isoscalar-isovector mixing of the collective excitations developing in neutron-rich systems. Focusing on the low-lying strength emerging in the isovector response, we show that this energy region essentially corresponds to the excitation of isoscalar-like modes, which also contribute to the isovector response owing to their mixed character. Considering effective interactions which mostly differ in the isovector channels, we observe that these mixing effects increase with the slope of the symmetry energy at saturation density, leading to a larger strength in the low-energy region of the isovector response. This result appears connected to the increase, with , of the neutron-proton asymmetry at the surface of the considered nuclei, i.e., to the neutron skin thickness.
8 More- Received 22 February 2016
- Revised 18 May 2016
DOI:https://doi.org/10.1103/PhysRevC.94.014313
©2016 American Physical Society