Confronting next-leading BFKL kernels with proton structure function data

We propose a phenomenological study of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) approach applied to the data on the proton structure function F-2 measured at HERA in the small-x(Bj) region. In a first part we use a simplified "effective kernel" approximation leading to few-parameter fits of F-2. It allows for a comparison between leading-logs (LO) and next-to-leading logs (NLO) BFKL approaches in the saddle-point approximation, using known resummed NLO-BFKL kernels. The NLO tits give a qualitatively satisfactory account of the running coupling constant effect but quantitatively the chi(2) remains sizeably higher than the LO fit at fixed coupling. In a second part, a comparison of theory and data through a detailed analysis in Mellin space x(Bj) -> w, leads to a more model independent approach to the resummed NLO-BFKL kernels we consider and points out some necessary improvements of the extrapolation at higher orders. (c) 2005 Elsevier B.V. All rights reserved.