DOORWAY STATE APPROXIMATION AND SIGN CORRELATIONS IN PARITY NONCONSERVATION IN COMPOUND NEUTRON RESONANCES

The nonzero average parity-nonconserving longitudinal analyzing powers for p-wave neutron resonances in compound nuclear systems are analyzed within the giant J=0- resonance doorway model. Assuming that the parity-nonconservation interaction can be approximated by a one-body operator of the type sigma.p, we find that the observed fixed sign of the asymmetry arises naturally within the doorway model. The J=0- giant resonance does not enhance the size of the constant asymmetry. The model prediction for the average symmetry is shown to be similar to that obtained in the single-particle model. In particular, if one retains only the first-order contribution to the analyzing power, a very large single-particle matrix element [4p1/2\V(pv)\5s1/2] congruent-to 75+/-50 eV is needed to reproduce the observed average asymmetry. This large value is in contradiction with the value of 2 eV estimated from the experimentally measured spreading width of the parity-violating interaction using the doorway model.