An Improved Test of the Flavor Independence of Strong Interactions

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).