on Meson-Nucleon Physics and the Structure of the Nucleon

The description of the decays J/ψ → φpi+pi−, J/ψ → ωpi+pi−, J/ψ → φK+K − and J/ψ → ωK+K − in terms of the scalar form factors of the light pseudoscalar mesons is reviewed. Key features in these decays include the S-wave resonances σ and f0(980), which appear prominently in the new data from the BES collaboration. These resonances are dynamically generated by resummation of the s-channel unitarity loops, after which the formalism is matched to the NLO expressions for the scalar form factors in Chiral Pertur-bation Theory (ChPT). This allows for an estimation of several low-energy constants (LECs) of ChPT, in particular the OZI-suppressed Lr4 and L r 6