Experimental results on the electroweak interaction

Abstract

Recent results from the four experiments ALEPH, DELPHI, L3 and OPAL at the Large Electron-Positron collider, LEP at CERN, and by the SLD collaboration at the Stanford Linear Collider, SLC, are reviewed. Analyses from an integrated luminosity of about 150 pb − recorded by each experiment at LEP, taken at different centre-of-mass energies within ±3 GeV around the peak of the Z resonance during the years 1989 to 1995 are available now. Repeated accurate calibrations of the beam energy lead to precise measurements of the mass and of the total width of the Z boson. These results are complemented by measurements at the Z resonance with polarised beams at Stanford. First results from an integrated luminosity of close to 100 pb −1 per experiment above the threshold for W boson pair production were also presented recently by the LEP collaborations. Together with measurements of the top quark and W boson masses at the Tevatron pp̄ collider at Fermilab these results provide tests of the Standard Model of the electroweak interaction with unprecedented precision and permit to place stringent limits on the mass of the Higgs boson, the last free parameter of the model.