Finite-t and target-mass corrections to deeply virtual compton scattering.

We carry out the first complete calculation of kinematic power corrections ~t/Q(2) and ~m(2)/Q(2) to the helicity amplitudes of deeply virtual Compton scattering. This result removes an important source of uncertainties in the quantum chromodynamics predictions for intermediate momentum transfers Q(2) ~ 1-10 GeV(2) that are accessible in the existing and planned experiments. In particular, the finite-t corrections are significant and must be taken into account in the data analysis.