Measurement of Ac with charmed mesons at the SLAC Large Detector

We present a direct measurement of the parity-violation parameter Ac in the coupling of the Z0 to c quarks with the SLD detector. The measurement is based on a sample of 530 k hadronic Z0 decays, produced with a mean electron-beam polarization of |Pe|=73%. The tagging of c-quark events is performed using two methods: the exclusive reconstruction of D*+, D+, and D0 mesons, and the soft pions (πs) produced in the decay of D*+→D0πs+. The large background from D mesons produced in B hadron decays is separated efficiently from the signal using precision vertex information. The combination of these two methods yields Ac=0.688±0.041.