A Measurement of Rb using a Vertex Mass Tag

TL;DR

This paper presents a precise measurement of the ratio Rb, representing the Z boson decay rate into b-quarks relative to all hadronic decays, using advanced vertex detection techniques on a large dataset from the SLD experiment.

Contribution

The study introduces a double tag method based on vertex mass reconstruction, achieving high b-tagging efficiency and purity with the SLD's CCD vertex detector, providing a new precise Rb measurement.

Findings

Measured Rb = 0.2142 with uncertainties

Achieved high b-tagging efficiency and purity

Utilized 3-D vertexing with CCD detector

Abstract

We report a new measurement of Rb = Gamma(Z0->b-bbar) / Gamma(Z0->hadrons) using a double tag technique, where the b hemisphere selection is based on the reconstructed mass of the B hadron decay vertex. The measurement was performed using a sample of 130k hadronic Z0 events, collected with the SLD at the SLC. The method utilizes the 3-D vertexing abilities of the CCD pixel vertex detector and the small stable SLC beams to obtain a high b-tagging efficiency and purity. We obtain Rb=0.2142+/-0.0034(stat.)+/-0.0015(syst.)+/-0.0002(R_c).