Nuclear skin and the curvature of the symmetry energy

TL;DR

This paper investigates how the interplay between the slope and curvature of the symmetry energy influences nuclear ground state properties, especially the neutron skin of lead-208, using advanced modeling techniques.

Contribution

It introduces a meta-modelling approach to explore the effects of symmetry energy parameters independently, highlighting the significance of the curvature parameter on neutron skin predictions.

Findings

Curvature parameter significantly affects neutron skin thickness.

Correlation between slope and curvature reduces the curvature's impact in Skyrme models.

Meta-modelling provides a flexible framework for exploring nuclear matter properties.

Abstract

The effect of correlations between the slope and the curvature of the symmetry energy on ground state nuclear observables is studied within the extended Thomas-Fermi approximation. We consider different isovector probes of the symmetry energy, with a special focus on the skin of $^{208}{\rm Pb}$. We use a recently proposed meta-modelling technique to generate a large number of equation of state models, where the empirical parameters are independently varied. The results are compared to a set of calculations using 17 different Skyrme interactions. We show that the curvature parameter plays a non-negligible role on the neutron skin, while the effect is reduced in Skyrme functionals because of the correlation with the slope parameter.