We have shown that, provided that the nonperturbative input is regular at the right of the ω=0 singularity of the dominant DGLAP anomalous dimension, the rise of F2 at small x, experimentally measured by the averaged observable [Formula: see text], is input-independent in the perturbative Q2 regime at small x. [Formula: see text] appears to be more input-dependent in the same range. The GRV-type parametrizations verify these properties. Other models, namely the BFKL kernel (QCD dipoles), DGLAP (with a nonperturbative input singular at the right of the ω=0) give different predictions for λ. At moderate Q2, there is a possibility of distinguishing these different perturbative QCD predictions in the near future.
Small-x physics in perturbative QCD