  Combining large $N_C$ techniques and partial wave dispersion theory to
analyze the $\pi\pi$ scattering, without relying on any explicit resonance
lagrangian, some interesting results are derived: (a) a general KSRF relation
including the scalar meson contribution; (b) a new relation between resonance
couplings, with which we have made an intensive analysis in several specific
models; (c) low energy constants in chiral perturbation theory related with
$\pi\pi$ scattering in terms of the mass and decay width of resonances.
