Sum rules for hadronic contributions to low-energy light-by-light   scattering
  We present a set of sum rules relating the low-energy light-by-light scattering to integrals of \gamma\gamma-fusion cross sections and use them to study the hadronic contributions. 
Vladimir Pascalutsa, Vladyslav Pauk, Marc Vanderhaeghen (Inst.   Kernphys., Mainz U.)
hep-ph nucl-th physics.optics