The parton picture of elementary particles

Abstract

The parton theory is developed along several lines. We begin by developing quantum mechanics in the infinite momentum frame. The Galilean analogy is worked out and the use of non-relativistic reasoning in relativistic contexts is illustrated. Applications of infinite momentum quantum mechanics include the computation of the radius of a relativistic bound state, space time visualization of the multiperipheral model, and the eikonal approach to high energy scattering. The classic phenomenological applications of the parton model are reviewed and explained. These include deep inelastic electroproduction, the shrinking photon effect and heavy lepton pair production. The string-model of hadrons is formulated in the infinite momentum frame as a parton model. We consider currents and the distribution of spins among the partons of the hadronic string. We suggest that it is profitable to view a hadron as a one-dimensional lattice of spins and isospins and show that many of the properties of the lattice can be related to the meson spectrum. Applications of the spin lattice idea are made to deep inelastic electron and neutrino scattering. Predictions are made for the behavior of the structure functions in these processes. Multiparticle production is examined in the string model. We derive the distribution of secondaries in longitudinal and transverse momentum, the charge per secondary as a function of rapidity and the correlations among secondaries at different rapidities. Speculations are made about a class of phenomena which go beyond the string model. These phenomena we call hard parton effects. They include the production of large transverse momenta among secondaries, logarithmically increasing total cross sections and power behaviors of wide angle exlusive cross sections. We conclude with some speculations about the breakdown of the parton model.