Density dependence of the symmetry energy from neutron skin thickness in finite nuclei

Abstract

Abstract. The density dependence of the symmetry energy around saturation density, characterized by the slope parameter L, is studied using information provided by the neutron skin thickness in finite nuclei. An estimate for L is obtained from experimental data on neutron skins extracted from antiprotonic atoms. We also discuss the ability of parity-violating elastic electron scattering to obtain information on the neutron skin thickness in 208 Pb and to constrain the density dependence of the nuclear symmetry energy. The size and shape of the neutron density distribution of 208 Pb predicted by mean-field models is briefly addressed. We conclude with a comparative overview of the L values predicted by several existing determinations.

Neutron skin thickness from the measured electric dipole polarizability inNi68,Sn120, andRoca-Maza1, Viñas2, Centelles3 et al. 2015Phys. Rev. CSelf Cite225322543View full textAdd to dashboardCite

“…The range for the slope of the symmetry energy L predicted by the subset of selected EDFs lies at the lower end of accepted values when compared to other analysis (see, e.g., Refs. [56][57][58]), yet it is consistent with studies involving giant resonances [59]. We emphasize that the limits deduced in the present work follow from the analysis of relatively clean electromagnetic experiments.…”

“…These estimates are consistent with other predictions of the neutron skin thickness, J, and L extracted from various experiments that include heavy-ion collisions, giant resonances, antiprotonic atoms, hadronic probes, polarized electron scattering, as well as astrophysical observations; see, e.g., Refs. [53,54,57,59,61]. Finally, the correlation between the electric dipole polarizabilities in 68 Ni, 120 Sn, and 208 Pb shows that almost all the EDFs that reproduce the measured polarizability in 208 Pb also reproduce the measured polarizabilities in 68 Ni and 120 Sn.…”

Neutron skin studies in heavy nuclei with coherent p0 photo-production

“…Neutron skin thickness ∆R np of 208 Pb as a function of the slope parameter L of the symmetry energy at saturation density [14]. The linear correlation given from different theoretical predictions is shown.…”

Density dependence of the nuclear symmetry energy from measurements of neutron radii in nuclei

“…(7) to the 26 experimental values of the NST displayed in Fig.2 (see Refs. [31,35] for details). From this fitting procedure we find that the slope of the symmetry energy estimated from experimental data of antiprotonic atoms lies in the range 30 ≤ L ≤ 80 MeV, which points towards a rather soft nuclear symmetry energy.…”

“…To extract this quantity from available experimental data is not an easy task and usually some model assumptions have to be made in order to connect the data with the parameter L. Different observables and methods have been considered to estimate these parameters (a sample of different experimental results and some theoretical calculations used to estimate L can be found, for instance, in Figure 1 of Ref. [31]). Although very different observables and methods have been used to extract L, there is a common range, approximately between 50 MeV and 70 MeV, where the different estimates of L have a large overlap.…”