Study of photon electroproduction on the nucleon at high and low energy by Virtual Compton Scattering

Virtual Compton Scattering (VCS) and Deeply Virtual Compton Scattering (DVCS) on the nucleon are two processes accessed via the photon electroproduction reaction (eN → eγN). In the first part of this paper we are interested by the DVCS on the neutron. We measured the (D(e, eγ)X-H(e, e'γ)X) unpolarized cross section and we extracted, for the first time, a non-zero contribution of (neutron-DVCS + coherent- deuteron-DVCS) at Q ² = 1.75 GeV² and x _B = 36 from Jefferson Lab experiment E08-025. VCS on the proton has been studied at Mainz Microtron MAMI at the four-momentum transfer squared Q ² = 0.5 GeV², below the pion production threshold. In the second part of this paper we present our preliminary results of the structure functions (P _LL ? (P _TT/ε)) and P _LT, and the electric and magnetic generalized polarizabilities α _E (Q ²) and β _M (Q ²) extracted from this experiment.