The QCD gluon ladders and HERA structure function
  We report on the extension of the data fitting considering the QCD inspired model based on the summation of gluon ladders applied to the $ep$ scattering. In lines of a two Pomeron approach, the structure function $F_2$ has a hard piece given by the model and the remaining soft contribution: a soft Pomeron and non-singlet content. In this contribution, we carefully estimate the relative role of the hard and the soft pieces from a global fit in a large span of $x$ and $Q^2$. 
A. Lengyel (IEP, National Academy of Sciences of Ukraine, Uzhgorod),   M.V.T. Machado (GFPAE, UFRGS)