Direct Measurement of A_b using Charged Kaons at the SLD Detector

TL;DR

This paper presents a new measurement of the asymmetry parameter A_b using vertex tagging and charged kaon identification at the SLD detector, achieving high efficiency and purity.

Contribution

It introduces a novel vertex tagging method combined with charged kaon identification to measure A_b with improved accuracy.

Findings

Measured A_b = 0.997 ± 0.044 ± 0.067

Achieved 78% b-hemisphere tagging efficiency

Achieved 97% purity in b-hemisphere selection

Abstract

We report a new measurement of A_b using data obtained by SLD in 1997-98. This measurement uses a vertex tag technique, where the selection of a b hemisphere is based on the reconstructed mass of the bottom 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 b-event tagging efficiency and purity of 78% and 97%, respectively. Charged kaons identified by the CRID detector provide an efficient quark-antiquark tag, with the analyzing power calibrated from the data. We obtain a preliminary result of A_b = 0.997 \pm 0.044 \pm 0.067