Impact of spin-orbit currents on the electroweak skin of neutron-rich nuclei

TL;DR

This paper investigates how spin-orbit currents influence the electroweak skin of neutron-rich nuclei, revealing significant effects that must be included in future nuclear structure calculations to match experimental precision.

Contribution

It demonstrates the substantial impact of spin-orbit currents on the electroweak skin, emphasizing their importance in accurate nuclear radius predictions.

Findings

Spin-orbit contributions significantly increase the electroweak skin in light neutron-rich nuclei.

These contributions are comparable to current experimental uncertainties.

Future models must include spin-orbit currents for precise electroweak form factor calculations.

Abstract

Background: Measurements of neutron radii provide important constraints on the isovector sector of nuclear density functionals and offer vital guidance in areas as diverse as atomic parity violation, heavy-ion collisions, and neutron-star structure. Purpose: To assess the impact of spin-orbit currents on the electromagnetic- and weak-charge radii of a variety of nuclei. Special emphasis is placed on the experimentally accessible electroweak skin, defined as the difference between weak-charge and electromagnetic-charge radii. Methods: Two accurately calibrated relativistic mean field models are used to compute proton, neutron, charge, and weak-charge radii of a variety of nuclei. Results: We find that spin-orbit contributions to the electroweak skin of light neutron-rich nuclei, such as 22O and 48Ca, are significant and result in a substantial increase in the size of the electroweak skin relative to the neutron skin. Conclusions: Given that spin-orbit contributions to both the charge and weak-charge radii of nuclei are often as large as present or anticipated experimental error bars, future calculations must incorporate spin-orbit currents in the calculation of electroweak form factors.