We have measured the differential cross sections for the production of $\pi^{ +}$, $K^{ +}$, $K^{ 0}$, $K^{ *0}$, $\phi$, p, $\Lambda$ and their corresponding antiparticles in separate samples of flavor-tagged $Z^{ 0}\to$ light-flavor ($u\bar{ u}$, $d\bar{ d}$, or $s\bar{ s}$), $Z^{ 0}\to c\bar{ c}$ and $Z^{ 0}\to b\bar{ b}$ events. Clear flavor dependences are observed, and the results are compared with the predictions of three fragmentation models. We have also performed a direct measurement of $A_{ s}$, 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 $A_{ s}$ = $0.82\pm 0.10(stat.)\pm 0.07(syst.)$.
Categories: hep-ex