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

TL;DR

This paper explores how electroweak parity-violating electron scattering can precisely determine the neutron skin thickness of 208Pb, thereby constraining the nuclear symmetry energy and its density dependence.

Contribution

It demonstrates a high linear correlation between parity-violating asymmetry and neutron skin thickness, enabling accurate extraction without assumptions on neutron density shape.

Findings

High linear correlation between asymmetry and neutron skin thickness

Method supports higher precision measurements in future experiments

Constraints on the density slope of nuclear symmetry energy

Abstract

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