B.I.Ermolaev (Ph T I , Petersburg)


New approach to QCD factorization


We show that both the $k_T$- and collinear factorization for 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 originated by the transverse momenta. Then, if the parton distribution has a sharp maximum in $k_{\perp}$, the $k_T$ factorization can be reduced to the collinear factorization. Our analysis excludes the use of the singular factors $x^{-a}$ (with $a > 0$) in the fits representing the initial quark and gluon distributions contributing to the DIS structure functions. This restriction is valid for all DIS structure functions in the framework of both the $k_T-$ and collinear factorizations.