Factorization in QCD and constraints on the non-perturbative contributions to the DIS structure functions

by Boris Ermolaev (IFMO Inst. of Fine Mechanics and Optics)

Thursday 2 Dec 2010, 11:00 → 12:00 Europe/Zurich

TH Common Room (CERN)

According to the factorization concept in QCD, the scattering amplitudes and the DIS structure functions can be represented as the convolutions of perturbative and non-perturbative blobs. For example, for the DIS off hadrons these blobs are the DIS off partons and the initial parton densities (IPD) respectively. The both blobs are infrared-sensitive, however their convolutions must be free of the ultraviolet (UV) and infrared (IR) divergences. First, we study the IR-properties of the perturbative contributions where we focus on the IR-dependence of the QCD coupling. Then we consider the IR-dependence of the non-perturbative contributions.
We show that the convolutions are UV- and IR- stable only if the IPD obey certain conditions, In particular, IPD for the singlet structure function F1 can contain the singular factors x^-a, however with a < 1 In contrast, IPD for other structure functions cannot contain the factors x^-a with positive a at all.