Constraints on the neutron skin and symmetry energy from the anti-analog giant dipole resonance inPb208

Abstract

We investigate the impact of the neutron-skin thickness, ∆Rnp, on the energy difference between the anti-analog giant dipole resonance (AGDR), EAGDR, and the isobaric analog state (IAS), EIAS, in a heavy nucleus such as 208 Pb. For guidance, we first develop a simple and analytic, yet physical, approach based on the Droplet Model that linearly connects the energy difference EAGDR−EIAS with ∆Rnp. To test this correlation on more fundamental grounds, we employ a family of systematically varied Skyrme energy density functionals where variations on the value of the symmetry energy at saturation density J are explored. The calculations have been performed within the fully selfconsistent Hartree-Fock (HF) plus charge-exchange random phase approximation (RPA) framework. We confirm the linear correlation within our microscopic apporach and, by comparing our results with available experimental data in 208 Pb, we find that our analysis is consistent with ∆Rpn = 0.204 ± 0.009 fm, J = 31.4 ± 0.5 MeV and a slope parameter of the symmetry energy at saturation of L = 76.4 ± 5.4 MeV -the attached errors correspond to a lower-limit estimate of the systematic plus experimental uncertainties. These results are in agreement with those extracted from different experimental data albeit, L and ∆Rpn, are somewhat large when compared to previous estimations based on giant resonance studies.

Theoretical estimates of supernova-neutrino cross sections for the stable even-even lead isotopes: Charged-current reactions

“…This is even more than for the presently studied three stable Pb isotopes. A more recent study of 208 Pb, using different SAMi-J Skyrme functionals, records similar fluctuations in the location of the IAS depending on the adopted symmetry energy of the functional at the saturation density of nuclear matter [42]. The present study and the other two, quoted above, show that the location of the IAS varies by a few MeV depending on the adopted Skyrme parametrization.…”

Nuclear equation of state from ground and collective excited state properties of nuclei

“…By comparing the energy differences between AGDR and IAS, calculated using various EDFs with the experimental data, the values of ∆r np , as well as the symmetry energy parameters could be constrained. Linear dependence between the energy difference E AGDR −E IAS has also been confirmed in the approach based on the nuclear droplet model [503]. Clearly, measurements of the AGDR with rare isotope beams will open novel perspectives to determine the neutron skin thickness in exotic nuclei [504].…”

“…60 shows the comparison of the constraints on the symmetry energy J and slope parameter L at saturation density determined from the AGDR in 208 Pb, in comparison to the ranges of values from other investigations based on modeling and experimental data on other nuclear phenomena (more details are given in Ref. [503], figure is the update from [506]). As shown in the figure, considerable differences are obtained for the AGDR constraint on L, that may have its origin in the model dependence in the EDFs employed in the analysis.…”

Impact of the surface energy coefficient on the deformation properties of atomic nuclei as predicted by Skyrme energy density functionals

“…[119] or the SAMi-based parametrizations of Refs. [120,121]. Indeed, only families of fits that systematically vary a single property of the EDF allow for controllable correlation analyses.…”