πNCharge-Exchange Scattering and theρTrajectory

$\pi N$ charge-exchange scattering is considered within the Regge framework. Among meson exchanges only $\rho$ exchange is possible in this reaction. On the basis of the nucleon electromagnetic-structure data it is found that at the momentum-transfer variable $t={m_{\rho }}^2$ the ratio of the spin-flip to non-spin-flip residues is quite large, ∼4.5, and arguments are given in favor of an even larger ratio, ∼20, at $t=0\mathrm{}$. This latter result helps explain the hump near the forward direction in the charge-exchange differential cross section. With the $\rho$ trajectory and residues consistent with the ${\pi }^{\pm }p$ total and differential cross-section data, good fits for $-t<~0.5 {\left(\frac{\mathrm{BeV}}{c}\right)}^2$ are obtained to the recent ${\pi }^{-}+p\to {\pi }^0+n$ data between 9 and 18 $\frac{\mathrm{BeV}}{c}$.