A TEST OF THE FLAVOR INDEPENDENCE \\[.1in] OF STRONG INTERACTIONS

TL;DR

This study tests whether the strong interaction coupling constants are flavor-independent by comparing measurements across light, charm, and bottom quarks in Z boson decays, finding results consistent with flavor independence.

Contribution

The paper provides experimental evidence supporting the flavor independence of the strong coupling constant across different quark flavors.

Findings

Measured ratios of strong couplings for different quark flavors are close to unity.

Results are consistent with the flavor independence hypothesis within uncertainties.

The analysis uses flavor-tagged multijet rates from Z decays at SLAC.

Abstract

We present a comparison of the strong couplings of light ($u$,~$d$,~and~$s$), $c$, and $b$ quarks determined from multijet rates in flavor-tagged samples of hadronic $Z^0$ decays recorded with the SLC Large Detector at the SLAC Linear Collider. Flavor separation on the basis of lifetime and decay multiplicity differences among hadrons containing light, $c$, and $b$ quarks was made using the SLD precision tracking system. We find: $\alpha_s^{uds}/{\alpha_s^{\rm all}} = 0.987 \pm 0.027({\rm stat}) \pm 0.022({\rm syst}) \pm 0.022({\rm theory})$, $\alpha_s^c/{\alpha_s^{\rm all}} = 1.012 \pm 0.104 \pm 0.102 \pm 0.096$, and $\alpha_s^b/{\alpha_s^{\rm all}} = 1.026 \pm 0.041 \pm 0.041\pm 0.030.$