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Role of the singular factors in the standard fits for initial parton densities

B. I. Ermolaev·M. Greco·S. I. Troyan
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Abstract

Total resummation of double- and single- logarithms of x contributing to the spin-dependent structure function g_1 ensures its steep rise at small $x$. In the asymptotic limit x ->0, the resummation leads to the Regge behavior of g_1 and allows to calculate the non-singlet and singlet intercepts of g_1. DGLAP lacks such a resummation but suggests special phenomenological fits for the initial parton densities such that the singular factors x^{-α} in the fits mimic the resummation and also provide g_1 with the steep (power-like) rise at the small-x region. Accounting for the total resummaton of logarithms of x allows to drop the singular factors in the fits and leads to remarkable simplifications of the fits.

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B. I. Ermolaev, M. Greco, S. I. Troyan. 2005-11-30. Role of the singular factors in the standard fits for initial parton densities. https://arxiv.org/abs/hep-ph/0511343

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