2007/07/12 by B. I. Ermolaev, M. Greco, Ermolaev, B. I. +3
Computer Science · Physics and Astronomy · #Computational Physics and Python Applications #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ph
paper · pdf · doi:10.48550/arxiv.0707.1764
Talk given at XV International Workshop on Deep-Inelastic Scattering and Related Subjects, 16-20 April 2007 Munich, Germany
arxiv created 2007/07/12 · openalex publication_date 2007/07/12 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The Standard Approach (SA) for description of the structure function g1 combines the DGLAP evolution equations and Standard Fits for the initial parton densities. The DGLAP equations describe the region of large Q2 and large x, so there are not theoretical grounds to exploit them at small x. In practice, extrapolation of DGLAP into the region of large Q2 and small x is done with complementing DGLAP with special, singular (~x-a) phenomenological fits for the initial parton densities. The factors x-a are wrongly believed to be of the non-perturbative origin. Actually, they mimic the resummation of logs of x and should be expelled from the fits when the resummation is accounted for. Contrary to SA, the resummaton of logarithms of x is a straightforward and natural way to describe g1 in the small-x region. This approach can be used at both large and small Q2 where DGLAP cannot be used by definition. Confronting this approach and SA demonstrates that the singular initial parton densities and the power Q2-corrections (or at least a sizable part of them) are rather not real physical phenomena but the artefacts caused by extrapolating DGLAP into the small-x region.