Small-X Behavior of Parton Densities at Low Q2 Values
  In the leading twist approximation of the Wilson operator product expansion with standard and "frozen" versions of strong copling constant we show that the Bessel-inspired behavior of the structure function $F_2$ at small $x$, obtained for a flat initial condition in the DGLAP evolution, leads to very good agreement with the deep inelastic scattering experimental data from HERA. 
A.Yu. Illarionov, A.V. Kotikov