Dispersion relation formalism for virtual Compton scattering and the   generalized polarizabilities of the nucleon
  A dispersion relation formalism for the virtual Compton scattering (VCS) reaction on the proton is presented, which for the first time allows a dispersive evaluation of 4 generalized polarizabilities at a four-momentum transfer $Q^2 \leq$ 0.5 GeV$^2$. The dispersive integrals are calculated using a state-of-the-art pion photo- and electroproduction analysis. The dispersion formalism provides a new tool to analyze VCS experiments above pion threshold, thus increasing the sensitivity to the generalized polarizabilities of the nucleon. 
B. Pasquini, D. Drechsel, M. Gorchtein, A. Metz, and M. Vanderhaeghen