Measurement of $A_c$ with Charmed Mesons at SLD

Abstract

We present a direct measurement of the parity-violation parameter $A_c$ in the coupling of the $Z^0$ to $c$-quarks with the SLD detector. The measurement is based on a sample of 530k hadronic $Z^0$ decays, produced with a mean electron-beam polarization of $|P_e|=73$. The tagging of $c$-quark events is performed using two methods: the exclusive reconstruction of $D^{\ast +}$, $D^{+}$, and $D^0$ mesons, and the soft-pions (${\pi }_s$) produced in the decay of $D^{\ast +}\to D^0{\pi }_s^{+}$. 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 $A_c=0.688\pm \mathrm{0.041.}$

36 pages 8 figures Latex, Submitted to Physical Review D