Constraining slope parameter of symmetry energy from nuclear structure

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 $\hat{I}{\pm }_D$, and $\hat{I}{\pm }_D{S}_0$ (i.e. product of $\hat{I}{\pm }_D$ 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 $\hat{I}{\pm }_D$ to $L$. It is found that the neutron skin thickness and $\hat{I}{\pm }_D{S}_0$ correlate well to $L$, and therefore are suitable for narrowing down the value of $L$ via experiments. The LED emergence and upgrowth makes the $\hat{I}{\pm }_D{S}_0$-$L$ correlation strong, although these correlations are disarranged when neutron halo appears in the ground state.

8 pages, 5 figures