Quark fragmentation in deep inelastic scattering

This review summarises the new results on deep inelastic scattering obtained by the European Muon Collaboration (EMC) in high energy interactions on protons, deuterium and nuclei. The basic quark-parton model (QPM) with the modifications given by quantum chromodynamics is known to give a good description of hadron production in lepton-nucleon interactions. However, data from previous muon experiments are limited by acceptance and cover mostly the forward region while those from neutrino experiments are mainly at low energy and do not offer a clean separation between current and target fragments. Both types of experiments are generally unable to identify charged particles. These limitations do not affect the new 280 GeV muon-proton data from NA9 which offer 4 π coverage for particles with P/sub lab/>100 MeV/c and particle identification over almost the full kinematical range. The general features of these data are described in the next section. The following ones will present successively a determination of the fragmentation functions, an analysis of correlation effects in azimuthal angle, rapidity and charge, and a comparison of multiplicities on various nuclear targets. Transverse momentum distributions and related QCD effects are not discussed in this review