Results on three-jet events in the UA2 detector at the CERN anti-pp Collider

The UA2 experiment, running at the CERN SPS anti-pp Collider, has performed a study of events containing three hard jets in the final state. The angular distributions of the three jets show evidence for both initial and final state bremsstrahlung, in good agreement with a QCD model to leading order in the strong coupling constant αsub(S). The yield of three-jet events relative to that of two-jet events provides a measure of the strong coupling constant: αsub(S) K3/K2 = 0.23 -+ 0.01 -+ 0.04, where K2 and K3 represent the contributions arising from higher order corrections in αsub(S) to the two and three jet exclusive cross-sections. 17 refs