Resolving the PREX-CREX puzzle in covariant density functional theory

The PREX-CREX puzzle, an apparent tension between parity-violating electron-scattering results for ${}^{208}$Pb and ${}^{48}$Ca revealed by modern density functional analyses, has posed a major challenge for nuclear theory. We show that this puzzle can be resolved within covariant density-dependent point-coupling density functional theory by introducing an enhanced isovector tensor coupling. A nonrelativistic reduction identifies the resulting strong isovector spin-orbit interaction as the key mechanism that reconciles the PREX and CREX measurements.