Retention of quantum numbers by quark and multiquark jets

Quantum-number retention in the fragmentation region of a jet is investigated as a means to identify and classify quark and multiquark systems in lepton- and hadron-induced reactions. We show that a simple "inside-outside" cascade model with a causal space-time structure predicts that the mean charge of hadrons in the jet fragmentation region equals the charge of the parent quark system modulo a universal constant ${\eta }_Q$ (the mean quark charge of the sea) confirming previous analyses. Specific tests are discussed, including deep-inelastic neutrino scattering, $e^{+}{e}^{-}$ annihilation with a strongly leading hadron, and massive-lepton-pair production. We emphasize that the Drell-Yan process could play a crucial role in testing these ideas for multiquark jets and identifying a possible "hole" fragmentation region. We also discuss the utility of using a charge-momentum vector as a discriminant of jet structure. Finally we emphasize the utility of charge-retention tests in large-$p_T$ hadronic reactions in order to discriminate between various contributing subprocesses.