The Higgs particle in the standard model: experimental results from LEP

At present, all the data obtained from the many experiments in particle physics are in agreement with the standard model. In the standard model there is one particle, the Higgs particle, that is responsible for giving masses to all particles with mass. In this sense, the Higgs particle occupies a unique position. Before the latter part of the year 2000, however, the Higgs particle was not observed experimentally. It is the purpose of this report to describe the first possible evidence for this particle, obtained by the four collaborations using the Large Electron-Positron colliding accelerator (LEP) at CERN, Geneva, Switzerland. The data were taken with the LEP centre-of-mass energy between 200 and 209 GeV. The result is dominated by the observation of an excess of four-jet events by ALEPH, one of the four experiments at LEP. Its mass, which is a free parameter in the standard model, is about 115 GeV/c².