Study of the four-jet anomaly observed at LEP centre-of-mass energies of 130 and 136 GeV

The four-jet events collected by DELPHI during the special LEP run at centre-of-mass energies of 130 and 136View the MathML source in 1997 with an integrated luminosity of View the MathML source are analysed. Their rate and the distributions of their di-jet masses, their smallest jet charges, and their di-jet charge separations all agree well with Standard Model predictions. Thus the hypothesis of pair production of a new particle with a sum of di-jet masses around View the MathML source is not supported. The combined result of the four LEP collaborations refuting this hypothesis at over 99% confidence level is also given.