Spin observables in low energy nucleon-antinucleon scattering

We discuss the model dependence of the spin parameters for low and medium energy antinucleon-nucleon ($\overline{N}N$) scattering. An $\overline{N}N$ potential model is used, consisting of a $t$-channel meson exchange part, supplemented by a complex annihilation potential, adjusted to reproduce the observed energy dependence of total elastic, inelastic, and charge exchange cross sections. A number of striking spin effects are predicted, particularly in the charge exchange channel. We explore the sensitivity of the effects to changes in the real and imaginary parts of the $\overline{N}N$ potential; in particular, we assess the possibility of extracting the strength of the coherent $\overline{N}N$ tensor potential due to $\pi$, $\rho$, and $\omega$ exchange from future data. Some implications of our results for future experiments are mentioned.