Experimental evidence for the non-Abelian nature of QCD from a study of multijet events produced ine+e−annihilation

Abstract

We present evidence for the non-Abelian nature of QCD from a study of multijet events produced in $e^{+}$ $e^{\mathrm{-}}$ annihilations from √s =50 to 57 GeV in the AMY detector at the KEK storage ring TRISTAN. A comparison of the three-jet event fraction at TRISTAN to the fraction of the DESY storage ring PETRA shows that the QCD coupling strength ${\alpha }_s$ decreases with increasing $Q^2$. In addition, measurements of the angular distributions of four-jet events show evidence for the triple-gluon vertex.