JETP Letters: issues online

The asymptotic freedom is known to split the leading- $\log$ BFKL pomeron into a series of isolated poles in the complex angular momentum plane. One of our earlier findings was that the subleading hard BFKL exchanges decouple from such experimentally important observables as small-x charm F₂^c, beauty F₂^b and the longitudinal structure functions of the proton at moderately large Q². For instance, we predicted precocious BFKL asymptotics of F₂^c(x,Q²) with intercept of the rightmost BFKL pole $\alpha_{{{\bf I\!P}}}(0)-1=\Delta_{{{\bf I\!P}}}\approx 0.4$ . On the other hand, the small-x open beauty photo- and electro-production probes the vacuum exchange for much smaller color dipoles which entails significant subleading vacuum pole corrections to the small-x behavior. In view of the accumulation of the experimental data on small-x F₂^c and F₂^b we extend our 1999 predictions to the kinematical domain covered by new HERA measurements. Our parameter-free results agree well with the determination of F₂^c, F_L and published H1 results on F₂^b but slightly overshoot the very recent (2008, preliminary) H1 results on F₂^b.