Improved test of the flavor independence of strong interactions

We present an improved comparison of the strong coupling of the gluon to light (q1=u + d+s), c, and b quarks, determined from multijet rates in flavor-tagged samples of hadronic Z° decays recorded with the SLC Large Detector at the SLAC Linear Collider between 1993 and 1995. Flavor separation among primary q1q̄1, cc̄, and bb̄ 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: αsc/αsuds =1.036±0.043(stat)-0.045+0.041(syst) -0.018+0.020(theory) and αsb/αsuds=1.004±0.018(stat)-0.031+0.026(syst)-0.029+0.018(theory). ©1998 The American Physical Society

Study of the structure of e(+)e(-)-\u3e b(b)over-bar-g events and first limits on the anomalous chromomagnetic coupling of the b quark

The structure of e+e-→bb̄g events was studied using Z0 decays recorded in the SLC Large Detector experiment at SLAC. Three-jet final states were selected and the charge-coupled device-based vertex detector was used to identify two of the jets as b or b. Distributions of the gluon energy and polar angle were measured over the full kinematic range for the first time, and compared with perturbative QCD predictions. The energy distribution is potentially sensitive to an anomalous b chromomagnetic moment κ. We measured κ to be consistent with zero and set the first limits on its value: -0.17<κ<0.11 at 95% C.L. ©1999 The American Physical Society