Large N_c behavior of light resonances in meson-meson scattering

Abstract

By scaling the parameters of meson-meson unitarized Chiral Perturbation Theory amplitudes according to the QCD large N_c rules, one can study the spectroscopic nature of light meson resonances. The scalars sigma, kappa f_0(980) and, possibly, the a_0(980) do not seem to behave as q-qbar states, in contrast to the vectors rho(770) and K*(892). The behavior shown by the scalars is naturally explained in terms of diagrams with intermediate $\bar{q}\bar{q}qq$-like states. Here we review our recent study and show how the results do not depend on the different fits to data.

Comments: 6 pages. To appear in the proceedings of the HADRON03 conference, Aschaffenburg, Germany. September 2003