Density dependence of the nuclear symmetry energy and neutron skin thickness in the KIDS framework

Abstract

The KIDS framework for the nuclear equation of state (EoS) and energy density functional (EDF) offers the possibility to explore systematically the effect of EoS parameters on predictions for a variety of observables. The EoS parameters can be varied independently of each other and independently of assumptions regarding the in-medium nucleon effective mass. Here I present a pilot study of the neutron skin thickness (NST) in nuclei of current interest. The results indicate that variations of the symmetry energy slope parameter L by roughly 10 MeV and variations of the droplet-model counterpart of the curvature parameter $K_{\tau }$ by roughly 20 MeV affect predictions by comparable amounts. However, structural details may also have sizable effects on predictions, notably in the cases of ${}^{68}$Ni and ${}^{208}$Pb. This work is part of a systematic investigation of the NST within the KIDS framework and of a broader effort to constrain the density dependence of the nuclear symmetry energy.

Comments: 6 pages incl. figure, 2 tables; prepared for HNPS Adv. Nucl. Phys. (Proc. 29th Symposium of the HNPS, September 2021); a complementary KIDS study with explicit neutron-star constraints can be found in arXiv:2112.00996