Virtual Compton Scattering at low energy and the generalized polarizabilities of the nucleon

Virtual Compton Scattering (VCS) γ*p → γp at low CM energy gives access to the Generalized Polarizabilities of the nucleon. These observables generalize the concept of electromagnetic polarizabilities to the case of a virtual photon. Dedicated VCS experiments have been performed at MAMI, Jefferson Lab and MIT-Bates. The experimental status is reviewed, including analysis methods and physics results. The measurement of absolute (ep → epγ) cross sections allows the extraction of the two unpolarized VCS structure functions PLL-PTT/ε and PLT, which are combinations of the Generalized Polarizabilities of the proton. Future prospects in the field of VCS at low energy are also presented