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The Status of ξ-Scaling

  • H. David Politzer
Part of the Studies in the Natural Sciences book series (SNS, volume 12)

Abstract

The logic of the “ξ-scaling” analysis of inclusive lepton-hadron scattering is reviewed with the emphasis on clarifying what is assumed and what is predicted. The physics content of several recent papers, which purport to criticize this analysis, in fact confirm its validity and utility. For clarity, I concentrate on the orthodox operator product analysis of electroproduction, local duality and precocious scaling. Other physics discussed includes the successes of QCD in the rate of charm production in muon inelastic scattering and in the energy-momentum sum rule. Gluons carry 30 ± 8% of the proton’s energy-momentum at Q2 = 3.5 GeV2. (Several considerations make this considerably smaller than previous estimates; the largest of these is the inclusion of gluon bremsstrahlung effects.)

Can QCD be tested against the available data on inclusive lepton scattering? This question appears absurd given that a major reason for interest in QCD is its explanation of the observed approximate scaling. Yet the question is serious, and its answer is complex. A recent series of papersl,2,3,4 addresses this issue and concludes that the answer is yes. Certainly, much of the evidence is qualitative and, at best, not even good for two significant figures. And since we still don’t know what a proton looks like in QCD, we may yet be barking up the wrong tree.

Keywords

Structure Function Operator Product Expansion Gluon Distribution Feynman Graph Final State Interaction 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media New York 1977

Authors and Affiliations

  • H. David Politzer
    • 1
  1. 1.Harvard UniversityCambridgeUSA

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