Abstract
By looking at the parity-nonconserving (PNC) asymmetries for different energies in (p) over right arrowp scattering, it is in principle possible to determine the PNC rho NN and omega NN couplings of a single-meson-exchange model of the PNC NN force. Analysis of the experimental data at 13.6, 45, and 221 MeV was performed by Carlson , [Phys. Rev. C 65, 035502 (2002)] who concluded the data were in agreement with the uncertainties accorded the original DDH estimates for the PNC meson-nucleon couplings. In this work it is shown first that a comparison with updated hadronic predictions of these couplings suggests the existence of some discrepancy for the PNC omega NN coupling. The effect of varying the strong coupling constants and introducing cutoffs in the one-boson-exchange weak potential is then investigated. As expected, the resulting asymmetry is quite sensitive to these parameters regardless of the energy. However, the above mentioned discrepancy persists. The dependence of this conclusion on various ingredients entering an improved description of the PNC NN force is also examined. Additional mechanisms include the two-pion resonance nature of the rho meson and some momentum dependence of the isoscalar PNC rho NN vertex. None of these corrections removes or even alleviates the above discrepancy. Their impact on the theoretical determination of the vector meson-nucleon couplings, the description of the PNC force in terms of single-meson exchange, and the interpretation of measurements are examined.
Published Version
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