Radiative decays with light scalar mesons and singlet-octet mixing in ChPT

We study different types of radiative decays involving f(0)(980) and a(0)(980) mesons within a unified ChPT-based approach at one-loop level. Light scalar resonances, which are seen in the pi pi, pi eta and K (K) over bar channels of the phi(1020) radiative decays and in the J/psi decays are responsible for key questions of low-energy dynamics in the strong interaction sector, and the decays phi(1020) -> gamma a(0)(980), phi(1020) -> gamma f(0)(980), a(0)(980) -> gamma gamma and f(0)(980) -> gamma gamma are of interest for current experimental programs in Juich, Frascati and Novosibirsk. From the theoretical point of view it is important to verify whether light scalar mesons are members of some flavor octet or nonet. We find a value for the mixing angle dictated by consistency with experiment and the coupling structures of the ChPT Lagrangian. The decay widths f(0)(980)/a(0)(980) -> gamma rho(770)/omega(782), which have not been experimentally studied yet, are predicted. We also obtain several relations between the widths, which hold independently of the coupling constants and which represent a fingerprint of the model.