Identi ed Hadron Production and Light Quark Fragmentation in Z 0 Decays

We have measured the di erential cross sections for the production of , K, K, K , , p, and their corresponding antiparticles in separate samples of avor-tagged Z ! lightavor (u u, d d, or s s), Z ! c c and Z ! b b events. Clear avor dependences are observed, and the results are compared with the predictions of three fragmentation models. We have also performed a direct measurement of As, the parity-violating coupling of the Z 0 to strange quarks, by measuring the left-right-forward-backward production asymmetry in polar angle of the tagged s quark. Our preliminary result is As = 0:82 0:10(stat:) 0:07(syst:). Presented at the International Euroconference on Quantum Chromodynamics (QCD 98), 2-8 July 1998, Montpellier, France Work supported by Department of Energy contracts: DE-FG0291ER40676 (BU), DE-FG0391ER40618 (UCSB), DE-FG0392ER40689 (UCSC), DE-FG0393ER40788 (CSU), DE-FG0291ER40672 (Colorado), DE-FG0291ER40677 (Illinois), DE-AC0376SF00098 (LBL), DE-FG0292ER40715 (Massachusetts), DE-FC0294ER40818 (MIT), DE-FG0396ER40969 (Oregon), DE-AC0376SF00515 (SLAC), DE-FG0591ER40627 (Tennessee), DE-FG0295ER40896 (Wisconsin), DE-FG0292ER40704 (Yale); National Science Foundation grants: PHY-9113428 (UCSC), PHY-8921320 (Columbia), PHY-9204239 (Cincinnati), PHY-9510439 (Rutgers), PHY-8819316 (Vanderbilt), PHY-9203212 (Washington); The UK Particle Physics and Astronomy Research Council (Brunel, Oxford and RAL); The Istituto Nazionale di Fisica Nucleare of Italy (Bologna, Ferrara, Frascati, Pisa, Padova, Perugia); The Japan-US Cooperative Research Project on High Energy Physics (Nagoya, Tohoku); The Korea Research Foundation (Soongsil, 1997).