The range of validity of the QCD-improved parton model

Based on the world DIS data we extract the experimental F 2 p − F 2 n as a function of Bjorken- x and photon virtuality Q 2, using two different methods. Both methods lead to identical results. We find that the standard PDFs fail to describe the experimental data below Q 2< 7 GeV 2, which is much...

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Bibliographic Details
Published in:Physics letters. B 2000-02, Vol.475 (1), p.120-126
Main Authors: Szczurek, A., Uleshchenko, V.
Format: Article
Language:English
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Summary:Based on the world DIS data we extract the experimental F 2 p − F 2 n as a function of Bjorken- x and photon virtuality Q 2, using two different methods. Both methods lead to identical results. We find that the standard PDFs fail to describe the experimental data below Q 2< 7 GeV 2, which is much higher than for F 2 p and F 2 d separately. The difference between PDFs and the experimental data cannot be understood as due to nuclear effects in the deuteron, and evidently suggests substantial nonsinglet higher-twist effects. The trend of the experimental data is approximately explained by a recent two-component model of the nucleon structure functions and suggests strong Q 2-dependence of the Gottfried Sum Rule, in disagreement with the parton model interpretation. The large negative higher-twist effects can explain the difference between the value of the Gottfried integral obtained recently by the E866 Drell-Yan experiment at Fermilab and an older NMC result.
ISSN:0370-2693
1873-2445
DOI:10.1016/S0370-2693(00)00066-6