Hadron production in deep inelastic lepton nucleus scattering

The comparison of hadron production in deep inelastic lepton scattering on different nuclei allows information to obtained about the reinteraction of the final state hadrons, because the projectile particle has pointlike structure and does not undergo multiple reaction with the target. A reduction in the multiplicity of fast forward produced hadrons was observed, which depends on the size of the target nucleus. This nuclear effect mainly depends on two kinematical variables, the virtual photon energy (ν) and the fraction of ν carried by the hadron observed (zh). The explanation of the characteristic ν-dependence is still an unsolved problem. The results of experiments performed in this field in the past 15 years are reviewed and discussed in the framework of intranuclear reinteraction models. A possible influence of the EMC effect on the hadron production in lepton nucleus scattering will also be considered. More detailed experimental information in the range of ν of 10-30 GeV would be very desirable in order to discriminate between competing predictions for the hadron formation time and, thus, to develop a more consistent picture of the fragmentation process. (orig.)