Q^2 evolution of parton distributions at small x. A study of   higher-twist effects
  We investigate the Q^2 evolution of parton distributions at small x values, obtained in the case of flat initial conditions. The contributions of twist-two and (renormalon-type) higher-twist operators of the Wilson operator product expansion are taken into account. The results are in excellent agreement with deep inelastic scattering experimental data from HERA. 
A. V. Kotikov, G. Parente