New look at the QCD factorization

TL;DR

This paper demonstrates how both k_T- and collinear factorization approaches in DIS structure functions can be derived from the Compton scattering amplitude through a series of approximations, clarifying their assumptions and relations.

Contribution

It provides a unified derivation of k_T- and collinear factorization from the Compton amplitude, highlighting the conditions under which each approximation is valid.

Findings

k_T- and collinear factorization are derived from Compton scattering amplitude

Transitions between factorization schemes depend on parton virtualities and distribution maxima

Conditions for reducing k_T- to collinear factorization are clarified

Abstract

We show that both the k_T- and collinear factorization for the DIS structure functions can be obtained by consecutive reductions of the Compton scattering amplitude. Each of these reductions is an approximation valid under certain assumptions. In particular, the transitions to the k_T- factorization is possible when the virtualities of the partons connecting the perturbative and non-perturbative blobs are space-like. Then, if the parton distribution has a sharp maximum in k_T, the k_T factorization can be reduced to the collinear factorization.