Highlights of Higgs Physics at LEP

Final results from the combined data of the four LEP experiments ALEPH, DELPHI, L3 and OPAL on Standard Model (SM) Higgs boson searches are presented. New preliminary results of searches in extended models are reviewed. Final results from the combined data of the four LEP experiments ALEPH, DELPHI, L3 and OPAL on Standard Model (SM) Higgs boson searches are presented. New preliminary results of searches in extended models are reviewed. The LEP experiments took data between August 1989 and November 2000 at centre-of-mass energies first around the Z resonance (LEP-1) and later up to 209 GeV (LEP-2). In 2000 most data was taken around 206 GeV. The LEP accelerator operated very successfully and a total luminosity of L = 2461 pb −1 was accumulated at LEP-2 energies. Data-taking ended on 3 November 2000, although some data excess was observed in searches for the SM Higgs boson with 115 GeV mass. In this report several different research lines are addressed: 1) the Standard Model Higgs boson: candidates, confidence levels, mass limit, coupling limits; 2) the Minimal Supersymmetric extension of the SM (MSSM): dedicated searches, three-neutral-Higgs-boson hypothesis, benchmark and general scan mass limits; 3) CP-violating models; 4) invisible Higgs boson decays; 5) flavour-independent hadronic Higgs boson decays; 6) neutral Higgs bosons in the general 2-doublet Higgs model; 7) Yukawa Higgs boson processes b ¯ bh and b ¯ bA; 8) singly-charged Higgs bosons; 9) doubly-charged Higgs bosons; 10) fermiophobic Higgs boson decays h→WW, ZZ, γγ. The results from Standard Model Higgs boson searches are final 1 , and the results of searches in extended models are mostly preliminary 2. Limits are given at 95% CL. 1 Standard Model Higgs Boson 1.1 Combined Test Statistics and Candidates Figure 1 shows that the observed SM excess is less than 2σ for combined LEP data, and lists the final candidates. The excess is reduced compared to previous reports. A short summary of the development of the data excess was given previously 3 .