A study of multi-jet events at the CERN antipp collider

The UA2 experiment has performed a study of events containing three hard jets in the final state. The angular distributions of the three jets show evidence for gluon bremsstrahlung, in good agreement with a QCD model to leading order in the strong coupling constant αS. The yield of three-jet events relative to that of two-jet events provides a measure of the strong coupling constant: αS K3/K2 = 0.23 ± 0.01 ± 0.04, where K2 and K3 represent the contributions arising from higher order corrections in αS to the two- and three-jet exclusive cross-sections. A preliminary study has also been performed on events containing four jets in the final state. The observed features of these events agree well with a recent leading order QCD calculations, indicating a strong deviation from phase space behavior. These results are not consistent with the presence of a large contribution from multi-parton scattering, in which more than one hard scattering takes place among the nucleon constituents. 12 refs.; 10 figs