Document Type

Article

Department/Program

Physics

Journal Title

Physical Review Letters

Pub Date

4-2021

Volume

126

Issue

17

Abstract

We report a precision measurement of the parity-violating asymmetry APV in the elastic scattering of longitudinally polarized electrons from 208Pb. We measure APV=550±16(stat)±8(syst) parts per billion, leading to an extraction of the neutral weak form factor FW(Q2=0.00616  GeV2)=0.368±0.013. Combined with our previous measurement, the extracted neutron skin thickness is Rn−Rp=0.283±0.071  fm. The result also yields the first significant direct measurement of the interior weak density of 208Pb: ρ0W=−0.0796±0.0036(exp)±0.0013(theo)  fm−3 leading to the interior baryon density ρ0b=0.1480±0.0036(exp)±0.0013(theo)  fm−3. The measurement accurately constrains the density dependence of the symmetry energy of nuclear matter near saturation density, with implications for the size and composition of neutron stars.

DOI

https://doi.org/10.1103/PhysRevLett.126.172502

Publisher Statement

This work is made available for educational and personal use only. Copyright is credited to the authors. Any other uses should be directed to the publisher.

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