Nucleon compton scattering at large momentum transfers

The authors have computed the helicity amplitudes for both the real and virtual nucleon Compton scattering at large momentum transfer in leading order perturbative QCD. The angular dependence of both the phases of the amplitudes and the cross sections are presented as a function of photon virtuality with different model distribution amplitudes. The singular numerical integration involved are handled by the method suggested by Kronfeld and Nizic. As pointed out before, at sufficiently high energies these predictions for virtual Compton Scattering can provide a stringent test of QCD.