Neutron skin of Pb-208, nuclear symmetry energy, and the parity radius experiment

A precise determination of the neutron skin Delta r(np) of a heavy nucleus sets a basic constraint on the nuclear symmetry energy (Delta r(np) is the difference of the neutron and proton rms radii of the nucleus). The parity radius experiment (PREX) may achieve it by electroweak parity-violating electron scattering (PVES) on Pb-208. We investigate PVES in nuclear mean field approach to allow the accurate extraction of Delta r(np) of Pb-208 from the parity-violating asymmetry A(PV) probed in the experiment. We demonstrate a high linear correlation between APV and Delta r(np) in successful mean field forces as the best means to constrain the neutron skin of Pb-208 from PREX, without assumptions on the neutron density shape. Continuation of the experiment with higher precision in APV is motivated since the present method can support it to constrain the density slope of the nuclear symmetry energy to new accuracy.