  In previous works, a squared mass operator M^2 and a more common centre of
frame Hamiltonian H_CM for the quark-antiquark system were obtained by using
the only assumption that ln W (W being the Wilson loop correlator) can be
written in QCD as the sum of its perturbative expression and an area term. We
evaluated the spectrum of these operators by neglecting all the spin-dependent
terms but for a spin-spin term. We succeeded in reproducing rather well the
entire meson spectrum and for the light-light systems we found straight Regge
trajectories with the right slope and intercepts. A first attempt to study the
contribution of the spin dependent terms has been made.
