The nucleon spin–orbit interaction is a cornerstone of nuclear structure theory, yet its isospin dependence remains insufficiently constrained within modern nuclear energy density functional (EDF) theory. It was recently shown that, within the framework of extended Skyrme EDFs, the charge-weak form factor difference ΔFCW in 48Ca exhibits remarkable sensitivity to the effective isovector spin–orbit (IVSO) interaction, whereas ΔFCW in 208Pb is much less sensitive to this channel. Extending this analysis to other nuclei, we find that 90Zr, with its ten spin–orbit unpaired 1g9/2 neutrons, displays a ΔFCW sensitivity to the IVSO strength similar to that of 48Ca, arising from modifications to the central mean-field potential rather than the one-body spin–orbit potential. In contrast, 62Ni, like 208Pb, remains largely insensitive to the IVSO interaction. This structure-driven distinction suggests an experimental strategy: future parity-violating electron scattering measurements, e.g., the MREX experiment at the MESA facility, on 48Ca and 90Zr would help constrain the effective IVSO strength, while measurements on 208Pb and 62Ni can provide a cleaner probe of the density dependence of the symmetry energy with reduced IVSO sensitivity.
Yue et al. (Tue,) studied this question.