We give a detailed account of the recently formulated generalised vector dominance/colour-dipole picture (GVD/CDP) of deep-inelastic scattering at low cursive Greek chi ≅ Q2/W2, including photoproduction. The approach, based on γ*(qq̄) transitions, qq̄ propagation and diffractive (qq̄)p scattering via the generic structure of the two-gluon exchange, provides a unique and quantitatively successful theory for the γ*p total cross section, σγ*p(W2, Q2), at low cursive Greek chi. The GVD/CDP is shown to imply the empirical low-cursive Grekk chi scaling law, σγ*p(W2, Q2) = σγ*p(η) with η = (Q2+ m20)/Λ2(W2), that was established by a model-independent analysis of the experimental data.
Cvetič, G., Schildknecht, D., Surrow, B., & Tentyukov, M. (2001). The generalised vector dominance/colour-dipole picture of deep-inelastic scattering at low cursive greek chi. European Physical Journal C, 77-91. https://doi.org/10.1007/s100520100650