A study of multi-jet events at the CERN p-bar p collider

Within the UA2 collaboration a study has been made 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: αsK3/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 calculation, indicating a strong deviation from phase space behaviour. 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. (author)