Search for the Standard Model Higgs Boson at LEP
Preliminary results from the four LEP experiments using data collected at 189 GeV have shown no evidence for the Standard Model Higgs boson. The preliminary 95% confidence level lower limits on the SM Higgs boson mass from ALEPH, DELPHI, OPAL, and L3 are 90.4 GeV, 94.1 GeV, 95.5 GeV, and 95.2 GeV, respectively. When LEP finishes in the year 2000, each experiment expects to collect 200 pb-1 of data at 200 GeV. These data will allow the discovery of the SM Higgs boson with a mass lower than about 105 GeV. Assuming that no new evidence for the SM Higgs boson is found, the mass exclusion limit would be approximately 110 GeV.