The BFKL-Regge factorization and $F_2^b$, $F_2^c$, $F_L$ at HERA: physics implications of nodal properties of the BFKL eigenfunctions

摘要

The asymptotic freedom is known to split the leading-$\log$ BFKL pomeron intoa series of isolated poles in the complex angular momentum plane. One of ourearlier findings was that the subleading hard BFKL exchanges decouple from suchexperimentally important observables as small-$x$ charm, $F_2^c$, and thelongitudinal, $F_L$, structure functions of the proton at moderately large$Q^2$. For instance, we predicted precocious BFKL asymptotics of $F_2^c(x,Q^2)$with intercept of the rightmost BFKL pole$\alpha_{\Pom}(0)-1=\Delta_{\Pom}\approx 0.4$. On the other hand, the small-$x$open beauty photo- and electro-production probes the vacuum exchange for muchsmaller color dipoles which entails significant subleading vacuum polecorrections to the small-$x$ behavior. In view of the accumulation of theexperimental data on small-$x$ $F_{2}^{c}$, $F_{2}^{b}$ and $F_{L}$ we extendour early predictions to the kinematical domain covered by new HERAmeasurements. Our parameter-free results agree well with the determination of$F_2^c$, $F_L$ and published H1 results on $F_2^b$ but slightly overshoot thevery recent (2008, preliminary) H1 results on $F_2^b$.