QCD dipole predictions for quark singlet, gluon and $F_L/F_T$ distributions at HERA

Abstract

In this contribution we apply the QCD dipole picture combined with $k_T$-factorization to get predictions for deep-inelastic scattering on an onium. Assuming renormalization-group factorization, we get predictions for the $F_2,F_G$ and $R=F_L/F_T$ proton structure functions. We obtain a three-parameter fit of the 1994 H1 data in the low-$x_{bj}$, moderate-$Q^2$ range. $F_G/F_2$ and $R$ are then predicted without any additionnal parameter. The BFKL dynamics contained in the dipole model is shown to provide a relevant model in describing the HERA data. The prediction for $F_2$ and $F_G$ are compatible with next-to-leading order DGLAP analysis. By contrast, $R$ is expected to be much lower at small $x_{bj}$.

Comments: 10 pages, latex file, 4 figures Talk given at the XXXIth Rencontres de Moriond QCD and High Energy Hadronic Interactions March 23-30, 1996, Les Arcs, France