Neutron-skin thickness of Pb-208 from the energy of the anti-analogue giant dipole resonance

The energy of the charge-exchange anti-analogue giant dipole resonance (AGDR) has been calculated for the Pb-208 isotope using the state-of-the-art fully self-consistent relativistic proton-neutron quasiparticle random-phase approximation based on the relativistic Hartree-Bogoliubov model. It is shown that the AGDR centroid energy is very sensitively related to the corresponding neutron-skin thickness. The neutron-skin thickness of Pb-208 has been determined very precisely by comparing the theoretical results with the available experimental data on E(AGDR). The result Delta R-pn = 0.161 +/- 0.042 agrees nicely with the previous experimental results