The color dipole BFKL-Regge expansion: from DIS on protons to pions to rise of hadronic cross sections

Abstract

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.

Comments: 12 pages Latex 2 PS figures, Revised version accepted for publication in Physics Letters B