Small x behavior of parton distributions. Analytical and "frozen" coupling constants. BFKL corrections

It is shown that in the leading twist approximation of the Wilson operator product expansion with “frozen” and analytic strong coupling constants, Bessel-inspired behavior of the structure functions F2 and F2cc and also the derivative d(ln F2)/d(ln(1/x)) at small x values, obtained for a flat initial condition in the DGLAP evolution equations, leads to good agreement with the deep inelastic scattering experimental data from HERA.