An Improved Test of the Flavor Independence of Strong Interactions

TL;DR

This paper provides an improved experimental test of whether the strong interaction coupling varies with quark flavor, using multijet rates from Z0 decays to compare couplings for light, charm, and bottom quarks.

Contribution

It introduces a refined method for flavor separation in Z0 decays, enabling more precise measurements of the flavor dependence of the strong coupling constant.

Findings

The ratio of charm to light quark strong coupling constants is approximately 1.036.

The ratio of bottom to light quark strong coupling constants is approximately 1.004.

Results are consistent with flavor independence of the strong interaction within uncertainties.

Abstract

We present an improved comparison of the strong coupling of the gluon to light (q_l=u+d+s), c, and b quarks, determined from multijet rates in flavor-tagged samples of hadronic Z0 decays recorded with the SLC Large Detector at the SLAC Linear Collider between 1993 and 1995. Flavor separation among primary q_l q_l-bar, c c-bar, and b b-bar final states was made on the basis of the reconstructed mass of long-lived heavy-hadron decay vertices, yielding tags with high purity and low bias against >= 3-jet final states. We find alpha_s^c/alpha_s^uds = 1.036+-0.043 (stat) +0.041-0.045 (syst) +0.020-0.018 (theory) and alpha_s^b/alpha_s^uds = 1.004+-0.018 (stat) +0.026-0.031 (syst) +0.018-0.029 (theory).