Dipole Model of theA2Meson and Charge-Exchange Scattering and Polarization

The $A_2$ meson is described as a dipole resonance and a linear Regge-dipole $A_2$ trajectory is assumed to dominate the charge-exchange process ${\pi }^{-}p\to \eta n$. A least-squares fit to the differential cross-section data for four adjustable parameters is performed, and leads to a ${\chi }^2=11\mathrm{}$ for 25 experimental points. A nonzero polarization is predicted. The multichannel problem corresponding to $A_2$ production in the process $\pi p\to A_{2}p$ is studied and a phase-shift model incorporating a dipole $A_2$ which produces different peaked structures in the various decay models is given by way of example.