Single-pion production and the structure of the weak neutral current

The restrictions of the structure of the weak neutral current imposed by single pion production cross sections on single nucleons are investigated. A general vector (V), axial-vector (A) neutral current with mod Delta I mod <or=1 is assumed, where the isovector V, A neutral currents are the neutral members of the isotriplets containing the charged weak currents. From neutrino cross sections alone bounds are derived for the neutral current coupling constants which supplement the known constraints from inclusive scattering. More specific assumptions about the isoscalar neutral current are also considered. It is shown that with the advent of antineutrino data for single pion production the neutral current coupling constants will be determined uniquely. (19 refs).