Parity-Nonconserving Nuclear Forces

The effective single-particle weak parity-nonconserving potential is recalculated including parity-nonconserving one-pion exchange forces and the two-body correlations induced by the hard cores in the nucleon-nucleon potential. The circular polarization of the $\gamma$ ray from the 482-keV transition in ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$ is calculated to be -(0.2±0.1)×${10}^{-4\mathrm{}}$. The measured value is -(0.06±0.01)×${10}^{-4\mathrm{}}$, showing that the observed parity nonconservation in nonleptonic $\Delta S=0\mathrm{}$ transitions is in agreement with the Cabibbo theory of weak interactions.