Isospin-1/2 nucleon-resonance production by a V, A weak neutral current

A set of ratios characterizing the production of the isospin-1/2 resonances D13(1514) and S11(1505), as well as the isospin-3/2 resonance P33(1232), by electromagnetic and weak (charged and neutral) currents are defined. Assuming the most general weak neutral current with V, A spatial structure, the matrix elements needed to extract the production ratios are calculated in three dynamical models for resonance production: the Born-approximation model, the nonrelativistic quark model, and the quark-bag model. For the special case of the Weinberg-Salam theory neutral current, the three models suggest that for 0 < or = sin2theta/subW/ < or = 0.5 the ratios D13/P33 and S11/P33 observed in neutral-current π0 or eta production on a free nucleon target should be substantially smaller (by a factor of 2 to 4) than the corresponding ratios observed in charged-current π0 or eta production. An attempt is made to predict the ratios D13/P33 and S11/P33 to be expected in charged-current production from the corresponding ratios observed in electroproduction, but here the three models do not agree, and so it is possible only to state a wide possible range in which the values of the ratios may lie. The charge-exchange corrections needed for comparison with experiments on complex nuclear targets are briefly discussed; it is found that for an aluminum target the reduction factors quoted above are halved, so that in neutral-current-induced reactions the ratios D13/P33 and S11/P33 are smaller by a factor of 1 to 2 than the corresponding ratios observed in charged-current--induced reactions