Charged- and neutral-current production of $\Delta \mathrm{}\left(1236\right)\mathrm{}$

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 $\Delta \mathrm{}\left(1236\right)\mathrm{}$. First we demonstrate that our model is in agreement with the Argonne data on charged-current production of the $\Delta$. We then study neutral-current $\Delta$ 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 Gürsey-Sikivie model. We fine that the results for the differential cross section in the forward region ($\left|q^2\right|\lesssim 0.1$ 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.