Constraining slope parameter of symmetry energy from nuclear structure

TL;DR

This study investigates how nuclear structure observables like neutron skin thickness and dipole polarizability relate to the slope parameter of symmetry energy, aiming to constrain its value through theoretical correlations.

Contribution

It compares correlations between the slope parameter and four nuclear structure quantities across different effective interactions, identifying the most reliable observables for constraining L.

Findings

Neutron skin thickness correlates well with L.

The product of dipole polarizability and symmetry energy also correlates strongly.

Neutron halo effects can disrupt these correlations.

Abstract

Four quantities deducible from nuclear structure experiments have been claimed to correlate to the slope parameter $L$ of the symmetry energy; the neutron skin thickness, the cross section of low-energy dipole (LED) mode, dipole polarizability $\alpha_D$, and $\alpha_D S_0$ (i.e. product of $\alpha_D$ and the symmetry energy $S_0$). By the calculations in the Hartree-Fock plus random-phase approximation with various effective interactions, we compare the correlations between $L$ and these four quantities. The correlation derived from different interactions and the correlation from a class of interactions that are identical in the symmetric matter as well as in $S_0$ are simultaneously examined. These two types of correlations may behave differently, as exemplified in the correlation of $\alpha_D$ to $L$. It is found that the neutron skin thickness and $\alpha_DS_0$ correlate well to $L$, and therefore are suitable for narrowing down the value of $L$ via experiments. The LED emergence and upgrowth makes the $\alpha_DS_0$-$L$ correlation strong, although these correlations are disarranged when neutron halo appears in the ground state.