Experimental tests of the quark-parton model

The quark-paxton model was developed in great detail in the previous chapter. Here we discuss the experimental situation and confront the theory with the vast amoimt of data on deep inelastic scattering and related reactions. It must be borne in mind that we have not yet discussed the QCD corrections to the model. These are not small, but their dominant effect can be taken into account by allowing the parton number densities to depend upon in a way calculable in QCD, so that, fortuitously, the entire formalism is basically unchanged, except that each qj x) — qj x,Q ). As mentioned earlier this implies a dynamical breaking of perfect Bjorken scaling. It also implies that if one is seeking accurate information about the qj x) from experiment then care must be taken to specify the involved. 

In this chapter we shall continue to write just qj x) but the above considerations should not be forgotten. 

We shall also look at some other reactions where the model provides a direct and successful description of the physics e e — hadrons, the Drell-Yan process hA + he — and the hadronic production of 

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Experimental tests of the quark-parton model Fig. 17.19. Quark model picture of e+e" —> hadrons. 

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