Four-jet final state production in e+e− collisions at centre-of-mass energies of 130 and 136 GeV

The four-jet final state is analyzed to search for hadronic decays of pair-produced heavy particles. The analysis uses the ALEPHdata collected at LEP in November 1995 at centre-of-mass energies of 130 and 136 GeV, corresponding to a total integrated luminosity of 5.7 pb−1. An excess of four-jet events is observed with respect to the standard model predictions. In addition, these events exhibit an enhancement in the sum of the two di-jet masses around 105 GeV/c 2. The properties of these events are studied and compared to the expectations from standard processes and to pair productionhypotheses.