Quark-Hadron Duality in Photoabsorption Sum Rules and Two Photon Decays   of Meson Resonances
  The idea of quark-hadron duality is developed and applied to integral sum rules for the photoexcitation of meson resonances. Some applications of the presented approach in the light and heavy quark sectors are made, and the role of the scalar diquark cluster degrees of freedom in the radiative formation of light scalar mesons is discussed. 
S.B.Gerasimov