E ects in Decays of Z 0 Bosons into Light Flavors

We present evidence for leading particle production in hadronic decays of the Z 0 boson to light-avor jets. A polarized electron beam was used to tag quark and antiquark jets, and a vertex detector was employed to reject heavy-avor events. Charged hadrons were identiied with a Cherenkov ring imaging detector. In the quark jets, more high-momentum p, , K , , and K 0 were observed than their antiparticles, and vice versa for antiquark jets, providing direct evidence that the higher-momentum particles in jets are more likely to carry the primary quark or antiquark from the Z 0 decay, and that s s production is suppressed in fragmentation.