Diffractive production and the total cross section in deep inelastic scattering

Original · EN

We explore the consequences for diffractive production, gamma* p --> X p, in deep inelastic scattering at low values of x Q²/W² <<1 that follow from our recent representation of the total photoabsorption cross section, sigmagamma* p, in the generalized vector dominance/ color dipole picture(GVD/CDP) 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-bar states that carry photon quantum numbers ("elastic diffraction"). Agreement with experiment in the W² and Q² dependence is found for Mₓ²/Q²<<1, where Mₓ 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 Mₓ. Our previous theoretical representation of the total photoabsorption cross section sigmagamma* p=sigmagamma* p(eta), in terms of the scaling variable eta=(Q²+m₀²)/Lambda²(W²) is extended to include the entire kinematic domain, x=<0.1 and all Q² with Q²>=0, where scaling in eta holds experimentally.