Author: Masako Iwasaki (U. of Oregon), representing the SLD Collaboration
Title: Measurements of $Z^0$ to Heavy-quark couplings at SLD
Abstract: We present measurements of $Z^0$ to heavy-quark coupling electroweak parameters, $R_b$, $R_c$, and parity-violation parameter $A_c$, from SLD.The measurements are based on approximately 550k hadronic $Z^0$ eventscollected in 1993-98.Obtained preliminary results of $R_b$ and $R_c$ measurements are$R_b = 0.2159 \pm 0.0014 \pm 0.0014$ and $R_c = 0.1685 \pm 0.0047 \pm 0.0043$.In the $A_c$ measurement, we use four methods to determine theinitial-quark charge:combined Kaon charge and Vertex charge, lepton, exclusively reconstructed D*, D-mesons, and a new method using inclusive soft-pion from D*.The preliminary results of these four methods were combined to give$A_c = 0.634 \pm 0.027$.
Comments: 5 pages Revtex, Contribution to DPF '99 Talk 0103Report-no: SLAC-PUB-8162Subj-class: experimental particle physics