PUB - Publikationen an der Universität Bielefeld

We explore the consequences for diffractive production, gamma*p-->Xp, in deep inelastic scattering at low values of xcongruent toQ(2)/W(2)much less than1 that follow from our recent representation of the total photoabsorption cross section, sigma(gamma*p), in the generalized vector dominance or color dipole picture that is based on the generic structure of the two-gluon exchange from QCD. Sum rules are derived that relate the transverse and the longitudinal (virtual) photoabsorption cross section to diffractive forward production of q (q) over bar states that carry photon quantum numbers ("elastic diffraction"). Agreement with experiment in the W-2 and Q(2) dependence is found for M-X(2)/Q(2)much less than1, where M-X is the mass of the produced system X. An additional component ("inelastic diffraction"), not actively contributing to the forward Compton amplitude, is needed for diffractive production at high values of M-X. Our previous theoretical representation of the total photoabsorption cross section, sigma(gamma*p)=sigma(gamma*p)(eta), in terms of the scaling variable etaequivalent to(Q(2)+m(0)(2))/Lambda(2)(W-2) is extended to include the entire kinematic domain, xless than or equal to0.1 and all Q(2) with Q(2)greater than or equal to0, where scaling in eta holds experimentally.