Spin Effects in High Energy Photon-Hadron Scattering in QCD

The spin effects at high energies and momenta transferred $|t|>1 GeV^2$ are analysed for quark-photon scattering. The energy independence of the ratio of spin-flip and spin-non-flip amplitudes in the same $\alpha_s$ order of QCD is obtained. It is shown that the contribution of the spin-dependent quark-pomeron vertex to the spin-flip amplitude is intensified by off-mass-shell effects in the quark loop. As a result, the magnitude of this amplitude can reach 20-30\% from a spin-non-flip one. The dependence of the cross-section on the form-factor and $\alpha_s^3$ spin-non-flip contributions are observed.