Comments on the large Nc behavior of light scalars

Abstract

I review the large Nc behavior of light resonances generated from unitarized one-loop Chiral Perturbation Theory. In contrast with the rho or K*, the scalar behavior is at odds with a qqbar "dominant component". In fact, in the light scalar region, meson-meson amplitudes vanish as Nc increases. Also, the scalar widths, obtained from their associated poles, behave as O(Nc^{1/2})<Gamma<O(Nc). We also clarify on the physical relevance of considering large Nc not too far from real life, Nc=3, and the interpretation of the mathematical Nc=infinity limit.