Direct Measurement of A_c using Inclusive Charm Tagging at the SLD Detector

摘要

We report a new measurement of A_c using data obtained by SLD in 1993-98.This measurement uses a vertex tag technique, where the selection of a chemisphere is based on the reconstructed mass of the charm hadron decay vertex.The method uses the 3D vertexing capabilities of SLD's CCD vertex detector andthe small and stable SLC beams to obtain a high c-event tagging efficiency andpurity of 28% and 82%, respectively. Charged kaons identified by the CRIDdetector and the charge of the reconstructed vertex provide an efficientquark-antiquark tag, with the analyzing power calibrated from the data. Weobtain a preliminary result of A_c = 0.603 \pm 0.028 \pm 0.023