Nature of the f_0(600) Scalar Meson from its N_c Dependence at Two Loops in Unitarized Chiral Perturbation Theory

摘要

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 qq dependence on the number of colors that, in contrast, is obeyed by the lightest vectors. The method suggests that a subdominant qq component of the f_0(600) possibly originates around 1 GeV.