Nature of the f_0(600) scalar meson from its N_c dependence at two loops in unitarized chiral perturbation theory

Abstract

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