Inelastic lepton-nucleon scattering

Abstract

The deep inelastic scattering of leptons (electrons, muons, neutrinos) by neutron and proton targets is reviewed. The main conclusion is that the processes involved can be interpreted in terms of a simple but powerful model, according to which leptons are scattered elastically by quasi-free point-like constituents (partons) of the nucleon, which subsequently interact to form the final hadronic state. The magnitudes of the cross sections and the values of certain sum rules identify the partons with quarks of fractional charge (+2e/3 and -e/3) and neutral vector gluons. At finite momentum transfers, there are observed to be small departures from the exact Bjorken scaling of the parton model, and these are discussed in terms of the quark-quark couplings. Anomalies in antineutrino scattering in one experiment indicate the possibility of further quark varieties.