  Elastic pi N scattering and the reaction pi+ p --> K+ Sigma+ are described
simultaneously in a unitary coupled-channels approach which respects
analyticity. SU(3) flavor symmetry is used to relate the t- and u-channel
exchanges that drive the meson-baryon interaction in the different channels.
Angular distributions, polarizations, and spin-rotation parameters are compared
with available experimental data. The pole structure of the amplitudes is
extracted from the analytic continuation.
