Neutron Skin of 208Pb, Nuclear Symmetry Energy, and the Parity Radius Experiment

Abstract

A precise determination of the neutron skin Δ r n p of a heavy nucleus sets a basic constraint on the nuclear symmetry energy ( Δ r n p 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 208 Pb . We investigate PVES in nuclear mean field approach to allow the accurate extraction of Δ r n p of 208 Pb from the parity-violating asymmetry A PV probed in the experiment. We demonstrate a high linear correlation between A PV and Δ r n p in successful mean field forces as the best means to constrain the neutron skin of 208 Pb from PREX, without assumptions on the neutron density shape. Continuation of the experiment with higher precision in A PV is motivated since the present method can support it to constrain the density slope of the nuclear symmetry energy to new accuracy.