First direct measurement of the parity-violating coupling of the Z0 to the s quark

We present the first direct measurement of A,, the parity-violating coupling of the Z(0) boson to the strange quark. using similar to 550000 e(+)e(-) --> Z(0) --> hadrons events recorded by the SLC Large Detector with a polarized e(-) beam. We tagged Z(0) --> s (s) over bar events by the absence of B or D hadrons and the presence in each hemisphere of a high momentum K+/- or K-s(0). Fitting the polar angle distributions of the strangeness-signed thrust axis gave A(s) = 0.895 +/- 0.066(stat) +/- 0.062(syst). The analyzing power and u (u) over bar + d (d) over bar background were constrained using the data, greatly reducing any model dependence.