Search for the Standard Model Higgs Boson at LEP

Abstract

The four LEP collaborations, ALEPH, DELPHI, L3 and OPAL, have collected 2465 pb-1 of e+e- collision data at energies between 189 and 209 GeV, of which 542 pb-1 were collected above 206 GeV. Searches for the Standard Model Higgs boson have been performed by each of the LEP collaborations. Their data have been combined and examined for their consistency with the Standard Model background and various Standard Model Higgs boson mass hypotheses. A lower bound of 114.1 GeV has been obtained at the 95% confidence level for the mass of the Higgs boson. The likelihood analysis shows a preference for a Higgs boson with a mass of 115.6 GeV. At this mass, the probability for the background to generate the observed effect is 3.4%.

27 pages, 13 figures. Figures supplied as .eps files. This note summarizes the LEP combined SM Higgs search results to be presented at EPS01 in Budapest, and at Lepton-Photon '01 in Rome. Submitted to CERN-EP preprints First update (v2): remove extraneous .eps files Second update (v3): Some minor corrections. 1-CLb(mh=115.6) -> 3.4% (was 3.5% before), "test signal curve" in fig. 1 updated. Cosmetic changes to figures v4: change word "revise" to "review" (was written assuming British meaning of the word)