Phenomenology of next-leading BFKL

We propose a phenomenological study of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) approach applied to the data on the proton structure function F2 measured at HERA in the small-xBj region (xBj < 0.01) and Q 2 in the range 5 to 120 GeV. With a simplified “effective kernel” approximation, we present a comparison between leading-logs (LO) and nextto-leading logs (NLO) BFKL approaches in the saddle-point approximation, using known resummed NLO-BFKL kernels. The LO result gives a very good description of the data with a three parameters fit of F2 but an unphysical value of the strong coupling constant, whereas the NLO two parameters fit leads to a qualitatively satisfactory account of the running coupling constant effect but quantitatively, for Q < 10 GeV, it fails to reproduce properly the data.