Pomeron in diffractive processes γ*(Q2)p→ρ0p and γ*(Q2)p→γ*(Q2)p at large Q2:: The onset of pQCD -: art. no. 074011

We study the reactions gamma*(Q(2))p-->rho(0)p and gamma*(Q(2))p-->gamma*(Q(2))p at large Q(2) and W-2/Q(2) and small momentum transfer, kappa(perpendicular to)(2) the nucleon where the Pomeron exchange dominates. At large Q(2) the virtual photon selects a hard q (q) over bar pair, thus selecting the hard Pomeron component (the BFKL Pomeron). The amplitudes for both transverse and longitudinal polarizations of the initial photon and outgoing rho-meson (photon) are calculated in the framework of the BFKL Pomeron exchange. Our calculations show that one cannot expect the early onset of the pure perturbative regime in the discussed diffractive processes: the small interquark distances, rho(q (q) over bar)<0.2 fm, start to dominate not earlier than at Q(2)similar or equal to 100 GeV2, W-2/Q(2)similar or equal to 10(7) in gamma*(Q(2))p -->rho(o)p and Q(2)similar or equal to 50 GeV2, W-2/Q(2) similar or equal to 10(6) in gamma*(Q(2))p --> gamma*(Q(2))p. [S0556-2821(99)02917-3].