Recent developments in U(3) ChPT: meson-meson scattering and finite   energy sum rules
  We discuss the meson-meson scattering and finite energy sum rule(FESR), based on the one-loop calculation within U(3) chiral perturbation theory. First we obtain the pertinent resonance spectroscopy from the unitarized partial wave scattering amplitudes. Then we investigate how well the FESR can be satisfied in the physical situation at Nc=3. Further discussions on the extrapolation of Nc are also given. 
Zhi-Hui Guo, J. A. Oller and J. Ruiz de Elvira
hep-ph