Predictions onπ−+p→ρ0+nand Some Related Processes Using Vector-Meson Dominance

In the usual application of vector-meson dominance to analyze the process ${\pi }^{-}+p\to {\rho }^0+n$, only the amplitudes for transversely polarized $\rho$ are related to single-pion photoproduction. In this paper, it is shown that both the longitudinal and the transverse amplitudes for the process ${\pi }^{-}+p\to {\rho }^0+n$ can be obtained from single-pion photoproduction amplitudes by assuming that the off-shell Ball amplitudes not only satisfy the constraints imposed by current conservation, but also are smooth in the vector-meson mass. The smoothness assumption is discussed in particle-exchange models in detail. We also extend our predictions to somewhat larger $\mathrm{}\left|t\right|\mathrm{}$ than in our previous work, and comparison is made with recent 15-GeV SLAC data on ${\pi }^{-}+p\to {\rho }^0+n$. We also apply the same assumptions to analyze some related processes such as the electroproduction of a charged pion.