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

TL;DR

This paper presents a new measurement of the charm asymmetry parameter A_c at the SLD using inclusive charm tagging with vertex reconstruction, achieving high efficiency and purity with a novel vertex-based method.

Contribution

It introduces a vertex tagging technique leveraging 3D vertexing and kaon identification to measure A_c with improved efficiency and purity.

Findings

Measured A_c = 0.603 1 0.028 1 0.023

High c-event tagging efficiency of 28%

Tagging purity of 82%

Abstract

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 c hemisphere 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 and the small and stable SLC beams to obtain a high c-event tagging efficiency and purity of 28% and 82%, respectively. Charged kaons identified by the CRID detector and the charge of the reconstructed vertex provide an efficient quark-antiquark tag, with the analyzing power calibrated from the data. We obtain a preliminary result of A_c = 0.603 \pm 0.028 \pm 0.023