SCALING IN γ*p TOTAL CROSS-SECTIONS, SATURATION AND THE GLUON DENSITY

Abstract

Including the new HERA data, the γ*p total cross-section is analyzed in the generalized vector dominance/color-dipole picture (GVD/CDP) that contains scaling in [Formula: see text], where Λ2(W2) is an increasing function of W2. At any Q2, for W2→∞, the cross-sections for virtual and real photons become identical, σγ*p (W2,Q2)/σγp (W2)→ 1. The gluon density deduced from the color-dipole cross-section fulfills the leading order DGLAP relationship. Evolution à la DGLAP breaks down for η≲0.1.