19 - The parton model and QCD

Summary

Introduction

In this chapter we will provide the parton model, the PM, with a QCD field theoretical structure according to the conventional method; for more details see e.g. In the next chapter we continue the discussion and present the Lund model version of the properties of deep inelastic scattering (DIS) events, both the treatment of the fragmentation and, in particular, the use of the newly developed linked dipole chain model, to provide the fragmenting string state.

The method of virtual quanta (MVQ) in Chapter 2 describes the electromagnetic field from a fast-moving charge in terms of the photon flux from the bremsstrahlung spectrum, and we will make use of this as an analogy. It is evident that Feynman picked up the basic features of the MVQ to make the PM into a description of the corresponding flux of the hadronic field quanta. In that way he made the PM into a useful tool to describe the cross sections for DIS events. Those we consider in this book are initiated by an electromagnetic probe, i.e. they correspond to inelastic electron-baryon (or muon-baryon) scatterings. But it is also possible to use the PM to describe e.g. inelastic neutrino-baryon scattering events as well as to consider the interactions between the partons themselves.

Feynman assumed that the partons can be treated as a stream of free elastic scatterers with respect to the probe.