Unitarity constraints and role of geometrical effects in deep-inelastic scattering and vector-meson electroproduction

Deep-inelastic scattering at low Bjorken x and elastic vector meson electroproduction are analyzed on the basis of the off-shell s-channel unitarity. We discuss behavior of the total cross-section of virtual photon-proton scattering and obtain, in particular, that the exponent in the power-like dependence of $\sigma^{tot}_{\gamma^* p}$ is related to the interaction radius of a constituent quark. The explicit mass dependence of the exponent in the power energy behavior of the vector meson electroproduction has been obtained. Angular distributions at large momentum transfers are considered. The energy dependence of the total cross-section of $\gamma^*\gamma^*$-interactions is also obtained.