Direct Measurement of Ab in Z0 Decays Using Charged Kaon Tagging

We present a direct measurement of the parity-violating asymmetry Ab in the Z0 to bb¯ coupling using a new technique to distinguish the b and b¯ quarks using charged kaons from B decays. The Z0 bosons are produced in e+e- collisions at the SLC with longitudinally polarized electrons. bb¯ events are selected using a secondary vertex mass tag and Ab is determined from the left-right forward-backward asymmetry. From the 1994–1995 data sample, selected from 100 000 hadronic Z0 decays, we obtain Ab=0.855±0.088stat±0.102syst.