A Preliminary Direct Measurement of the Parity Violating Coupling of the Z{sup 0} to Strange Quarks, A{sub s}

We present a preliminary direct measurement of the parity violating coupling of the Z{sup 0} to strange quarks, A{sub s}, derived from a sample of approximately 300,000 hadronic decays of Z{sup 0} produced with a polarized electron beam and recorded by the SLD experiment at SLAC between 1993 and 1997. Z{sup 0} {r_arrow} s{bar s} events are tagged by the presence in each event hemisphere of a high-momentum K{sup {+-}}, K{sub s}{sup 0} or {Lambda}{sup 0}/{bar {Lambda}}{sup 0} identified using the Cherenkov Ring Imaging Detector and/or a mass tag. The CCD vertex detector is used to suppress the background from heavy flavor events. The strangeness of the tagged particle is used to sign the event thrust axis in the direction of the initial strange quark. The coupling A{sub s} is obtained directly from a measurement of the left-right-forward-backward production asymmetry in polar angle of the tagged strange quark. To reduce the model dependence of the measurement, the background from primary up and down events is measured from the data, as is the analyzing power of the method for primary strange events. We measure: A{sub s} = 0.82 {+-} 0.10(stat.) {+-} 0.08(syst.)(preliminary)