Charged- and neutral-current production ofΔ(1236)

Abstract

Based on a quark-model approach previously developed by us which employs a ${q}^{2}$ continuation in terms of generalized meson-dominance form factors we study the weak production of the isobar $\ensuremath{\Delta}(1236)$. First we demonstrate that our model is in agreement with the Argonne data on charged-current production of the $\ensuremath{\Delta}$. We then study neutral-current $\ensuremath{\Delta}$ production using four different gauge models, namely, the standard Weinberg-Salam model, a vectorlike model with six quarks, a five-quark model due to Achiman, Koller, and Walsh, and a variant of the G\"ursey-Sikivie model. We fine that the results for the differential cross section in the forward region ($|{q}^{2}|\ensuremath{\lesssim}0.1$ Ge${\mathrm{V}}^{2}$) are very sensitive to the structure of the weak neutral current and suggest that measurements in this region constitute a stringent test of weak-interaction models. We also calculate the density-matrix elements measurable from decay correllations. The density-matrix elements are not so sensitive to the models containing some axial-vector contribution, whereas the vectorlike model shows a behavior quite distinct from the others.