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Celebrating CERN's discoveries and looking into the future |
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The ResultsDiscoveriesIn a packed CERN auditorium on the 20th and 21st of January 1983, UA1 and UA2 presented their first candidate Ws. At a Press Conference on the 25th, UA1 announced the discovery of the W boson. Summer brought the Zs. The characteristics of these long-awaited particles were just as the electroweak theory predicted.These discoveries were the culmination of theoretical inspiration, technological excellence, dedicated experimentation and team work on a scale never before seen in particle physics. This tremendous effort was rewarded in 1984 when Carlo Rubbia and Simon Van der Meer shared the Nobel physics prize. TodayThe electroweak theory is part of the so-called Standard Model, our best description of particles and their interactions. Extremely precise measurements of Ws and Zs at CERN have tested Standard Model predictions with high accuracy, to better than parts in a thousand, without revealing any flaws.This impressive work has been done at the Large Electron-Positron collider (LEP). Between 1989 and 1995 the four LEP experiments, ALEPH, DELPHI, L3 and OPAL, each collected some 4 million Zs from electron-positron collisions. Since 1996, when the LEP energy was doubled, W+ / W- pairs have been studied. On 14 August 1989, the first electron-positron collisions took place at LEP, with energies of 45 GeV on 45 GeV. The first Z was detected after just 16 minutes. TomorrowNewton discovered that weight is proportional to mass. Einstein discovered that energy is equivalent to mass. But neither explained the origin of mass. Could the Higgs boson be Nature’s mass donor? If not, what is?Higgs bosons have never been seen. They are expected to have a mass below 200 GeV. When LEP closed in the year 2000, it had searched very thoroughly for new particles up to 100 GeV. From 2007, CERN’s Large Hadron Collider (LHC) will smash protons together with ten times more energy than ever before. Whatever is giving mass to the Universe should show up in this unexplored region: if not Higgs bosons, then something even more exciting. The hunt is on. |