Study of the Reactionsνp→μ−Δ++at High Energies and Comparisons with Theory

We present production and decay distributions for the reaction $\nu p\to {\mu }^{-}p{\pi }^{+}$ with $M_{{\pi }^{+}p}<1.4\mathrm{}$ GeV. This reaction is primarily $\nu p\to {\mu }^{-}{\Delta }^{++}$, but we find evidence for the presence of non-$\Delta$ amplitudes for $Q^2>1\mathrm{}$ Ge${\mathrm{V}}^2$. The data are fitted by various theoretical models. For $Q^2<1\mathrm{}$ Ge${\mathrm{V}}^2$ the best fit yields the value $M_A={1.25}_{-0.13\mathrm{}}^{+0.15\mathrm{}}$ GeV, using a dipole-nucleon axial-vector form factor in Adler's model, although none of these models successfully reproduces the observed $\Delta$-decay distributions.