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B.I.Ermolaev (Ph T I , Petersburg)
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New approach to QCD factorization
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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.