PUB - Publikationen an der Universität Bielefeld

We examine the total cross section of virtual photons on protons, sigma(gamma*p)(W-2, Q(2)), at low xcongruent toQ(2)/W-2<<1 and its connection with "elastic'' diffractive production gamma(T,L)p* --> X(T,L)(J=1)p in the two-gluon exchange dynamics for the virtual forward Compton scattering amplitude. Solely based on the generic structure of two-gluon exchange, we establish that the cross section is described by the (imaginary part of the) amplitude for forward scattering of q (q) over bar vector states, (q (q) over bar (J=1)(T,L) p --> (q (q) over bar)(T,L)(J=1)p The generalized vector dominance picture is accordingly established to only rest on the two-gluon-exchange generic structure. This is explicitly seen by the sum rules that allow one to directly relate the total cross section to the cross section for elastic diffractive forward production, gamma*(T,L)p --> (q (q) over bar) (J=1)(T,L)p, of vector states.