  We address an actual problem of baryon-resonance dominated meson-exchange
processes in the low GeV regime, i.e. the phase and the structure of meson-NN*
transition vertices. Our starting point is a quark-diquark model for the
baryons (obeying approximate covariance; the mesons are kept as elementary
objects), together with the relative phases for the NN vertices, as determined
from low energy NN scattering. From the explicit representation of the N and N*
baryons, we exemplify the derivation of the coupling constants and form factors
of the NN*(1535,1/2-)transition vertices for pseudo-scalar, scalar and vector
mesons.
