Parton densities in a nucleon

A. L. Ayala*, M. B. Gay Ducati, E. M. Levin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

75 Scopus citations


In this paper we re-analyze the situation with the shadowing corrections (SC) in QCD for the proton deep-inelastic structure functions. We reconsider the Glauber-Mueller approach for the SC in deep-inelastic scattering (DIS) and suggest a new non-linear evolution equation. We argue that this equation solves the problem of the SC in the wide kinematic region where αSκ = αS(3παS/2Q2R2)xG(x, Q2) ≤ 1. Using the new equation we estimate the value of the SC which turn out to be essential in the gluon deep-inelastic structure function but rather small in F2(x, Q2). We claim that the SC in xG(x, Q2) is so large that the BFKL Pomeron is hidden under the SC and cannot be seen even in such "hard" processes that have been proposed to test it. We found that the gluon density is proportional to In(1/x) in the region of very small x. This result means that the gluon density does not reach saturation in the region of applicability of the new evolution equation. It should be confronted with the solution of the GLR equation which leads to saturation.

Original languageEnglish
Pages (from-to)355-395
Number of pages41
JournalNuclear Physics B
Issue number1-2
StatePublished - 2 Feb 1998


FundersFunder number
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Conselho Nacional de Desenvolvimento Científico e Tecnológico
Financiadora de Estudos e Projetos


    • Eikonal approximation
    • Evolution equations
    • Gluon structure function
    • Perurbative QCD


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