Parity nonconservation in proton scattering at higher energies

Parity-nonconservation experiments in the scattering of longitudinally polarized protons at incident proton momenta of 1.5 and 6 GeV/c are examined. These experiments indicate a change with energy of the total cross section correlated with proton helicity that was unexpected. This energy dependence is due to the strong part of the interaction and may indicate the role of a diquark component in the nucleon. New experiments at higher energies are needed to confirm such a model. Future experiments can benefit from an analysis of sources of systematic error that have been encountered in the experiments discussed here.