Single-spin asymmetry in DVCS: fragmentation region of polarised lepton
  For the kinematical region when a hard photon is emitted predominantly close to the direction of motion of a longitudinally polarized initial electron and relatively small momentum transfer to a proton we calculate the azimuthal asymmetry of photon emission. It arises from the interference of the Bethe-Heitler amplitude and those which are described by a heavy photon impact factor. Azimuthal asymmetry does not decrease in the limit of infinite cms energy. Lowest order expression for the impact factor of a heavy photon is presented. 
I.Akushevich (TJNAF), E. Kuraev, B. Shaikhatdenov (JINR)