Low energy theorem for virtual Compton scattering and generalized sum   rules of the nucleon
  We formulate the low energy theorem for virtual Compton scattering off a nucleon and examine its consequences for generalized nucleon polarizabilites. As a result of a new, model independent definition of the low energy limit for VVCS reaction, all generalized sum rules of the nucleon have continuous limit for real photons and obtain contributions from the $t$-channel that were not included previously. 
M. Gorchtein and A.P. Szczepaniak