Nonperturbative approach to effective chiral Lagrangians and meson interactions

We develop a coupled channel unitary approach describing the behavior at higher energies of systems whose low-energy dynamics is given by effective O(p^2) and O(p^4) chiral Lagrangians. Our free parameters are those of the O(p^4) Lagrangian. When applied to the meson-meson interaction, it yields a remarkable agreement with data up to √2≅1.2 GeV, dynamically generating the σ , f_0 α_0, ρ, and K* resonances. Further applications are also proposed