Two photon decays of scalar mesons in the quark NJL model
  Two photon decays of scalar mesons f_0(980), a_0(980), \sigma(600) in the quark Nambu - Jona - Lasinio (NJL) model are calculated. The contributions of the meson loops are taken into account along with the quark loops (Hartree - Fock approximation). This corresponds to the next order of the 1/N_c expansion, where   N_c=3 is the number of quark colors. It is shown that the meson and quark loops give comparable contributions to the amplitude. Moreover, in the process f_0(980)-> \gamma \gamma the kaon loop plays the dominant role. A similar situation takes place in the decay   \phi -> f_0(980) \gamma \cite{physrev}.   Our results are in satisfactory agreement with the recent experimental data. 
Yu. L. Kalinovsky, M. K. Volkov