Nuclear effects in photoproduction and leptoproduction

We discuss nuclear effects in hadronic final states in photoproduction and leptoproduction on nuclei. Whereas the final states in photoproduction and leptoproduction on free nucleons are similar, striking differences are predicted for the case of nuclear targets, the differences being largest in multiplicity correlations. Quantitative predictions are given for the cases of practical interest: photoproduction and muonproduction on emulsion nuclei, and neutrino-production in neon and propane-freon bubble chambers. Neutrino-production on nuclei is emphasized as offering the most direct test of the formation length hypotheses. (orig.)