As noticed by Fadin, Kuraev and Lipatov in 1975 incorporation of asymptotic freedom into the BFKL equation splits the QCD pomeron into a series of isolated poles in complex angular momentum plane. Following our earlier work on the proton structure function we explore the phenomenological consequences of the emerging BFKL-Regge factorized expansion for the small-$x$ structure function of the pion $F_{ 2\pi}(x,Q^2)$. We calculate $F_{ 2\pi}$ in a small-$x$ region and find good agreement with the recent H1 determination of $F_{ 2\pi}(x,Q^2)$. We also present the BFKL-Regge factorization based evaluation of the contribution from hard scattering to the observed rise of the $NN$, $\pi N$ and real photo-absorption $\gamma N$ and $\gamma \pi$ total cross sections.
Categories: hep-ph