Measurements of $Z^0$ to Heavy-quark couplings at SLD

TL;DR

This paper reports precise measurements of the Z boson's couplings to heavy quarks, specifically b and c quarks, using data from the SLD experiment, providing key electroweak parameters with multiple methods.

Contribution

It introduces new combined measurements of $R_b$, $R_c$, and $A_c$ using innovative charge determination techniques from a large dataset of hadronic Z decays.

Findings

Measured $R_b$ as 0.2159 ± 0.0014 ± 0.0014

Measured $R_c$ as 0.1685 ± 0.0047 ± 0.0043

Determined $A_c$ as 0.634 ± 0.027

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 $Z^0$ events collected 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 the initial-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 $A_c = 0.634 \pm 0.027$.