2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/81896Polarization phenomena are essential for the understanding of elementary processes, and are typically large in the threshold region. The selection rules with respect to P-parity, angular momentum, isotopic spin and the Pauli principle allow to parametrize in a model independent way, the spin structure of the matrix elements for the near-threshold heavy meson production in NN-collisions in terms of a small number of partial amplitudes. Such parametrization is very powerful for the analysis of polarization phenomena and possible $t-$exchange mechanisms.5 pages, one figure Contribution to the Summer school and Workshop on COSY Physics, 30 August-4 September, Yuelich, GermanyNuclear Theorytext