Nature of the f_0(600) from its N_c dependence at two loops in   unitarized Chiral Perturbation Theory
  By using unitarized two-loop Chiral Perturbation Theory partial waves to describe pion-pion scattering we find that the dominant component of the lightest scalar meson does not follow the q-qbar dependence on the number of colors that, in contrast, is obeyed by the lightest vectors. The method suggests that a subdominant q-qbar component of the f_0(600) possibly originates around 1 GeV. 
J. R. Pelaez and G. Rios