QCD effective charges and the structure function $F_2$ at small-$x$: Higher twist effects

Abstract

We consider the effect of higher twist operators of the Wilson operator product expansion in the structure function $F_2(x,Q^2)$ at small-$x$, taking into account QCD effective charges whose infrared behavior is constrained by a dynamical mass scale. The higher twist corrections are obtained from the renormalon formalism. Our analysis is performed within the conventional framework of next-to-leading order, with the factorization and renormalization scales chosen to be $Q^2$. The infrared properties of QCD are treated in the context of the generalized double-asymptotic-scaling approximation. We show that the corrections to $F_2$ associated with twist-four and twist-six are both necessary and sufficient for a good description of the deep infrared experimental data.

Comments: 19 pages, 6 figures, text improved, references added, gluon distribution function calculated. To be published in Phys. Lett. B