Polarization phenomena for vector-meson production induced by neutron-proton collisions in collinear kinematics

Polarization phenomena for vector-meson production in neutron-proton collis ions, n + p --> d + V-0, with V-0 = rho, omega, or phi, are studied for col linear kinematics when the vector mesons are produced at angles theta = 0 d egrees or 180 degrees with respect to the momentum of the incoming beam. It is shown that the spin structure of the matrix elements can be parametrize d in terms of five independent complex scalar amplitudes whose symmetry pro perties follow from the isotopic invariance of the strong interaction and f rom which specific polarization properties can be deduced. The polarization structure functions, calculated in terms of these five independent scalar amplitudes, allow to analyze one and two spin-polarization observables in a model-independent way.