  The TDA and RPA many-body methods are applied to a QCD motivated Hamiltonian
in the Coulomb gauge. The gluon effects in the low energy domain are accounted
for by the Instantaneous color-Coulomb Interaction between color-charge
densities, approximated by the sum of a Coulomb and a confining linear
potentials. We use the eigenfunctions of the harmonic oscillator as a basis for
the quantization of the quark fields, and discuss how suitable this basis is in
various steps of the calculation. We show that the TDA results already
reproduce the gross-structure of the light flavored meson states. The pion-like
state in the RPA description, which is a highly collective state, is in a
better agreement with the experimental value. The results are related to other
nonperturbative treatments and compared to experimental data. We discuss the
advantages of the present approach.
