  Using the local flavor SU(4) gauge invariance in the limit of vanishing
vector meson masses, we extend our previous study of charm meson scattering
cross sections by pion and rho meson, which is based only on the
pseudoscalar-pseudoscalar-vector meson couplings, to include also contributions
from the couplings among three vector mesons and among four particles. We find
that diagrams with light meson exchanges usually dominate the cross sections.
For the processes considered previously, the additional interactions lead only
to diagrams involving charm meson exchanges and contact interactions, and the
cross sections for these processes are thus not much affected. Nevertheless,
these additional interactions introduce new processes with light meson
exchanges and increase significantly the total scattering cross sections of
charm mesons by pion and rho meson.
