Friday, January 26, 2001, 16:00
WHGA Auditorium
P. Janot, CERN
Abstract:
The large Electron Positron collider (LEP) operated at CERN between
1989 and 2000, at centre-of-mass energies from 88 to 209.2 GeV. During these
eleven years of running, the theory of Particle Physics was tested with an
accuracy which will remain unrivalled for long, thus allowing its internal
consistency to be verified in great details. In 1999 and 2000, the LEP
performance was pushed to, and indeed beyond, the limits of what has been
believed possible in view of maximizing the Higgs boson discovery potential. In
the last months of 2000, the centre-of-mass energy reached 206 GeV and more. It
seemed that the effort had paid off when the signals at 115 GeV appeared, were
confirmed, and were then confirmed again. In spite of these tantalizing hints,
LEP was stopped on November 2, 2000, without convincing explanations.
In the first part of the seminar ("La Vita e' Bella"), I will briefly summarize the Physics outcome of LEP, with a special emphasis on what LEP brought to the overall understanding of the theory. In the second part ("ApocalHiggs Now"), I will explain how the signals at 115 GeV appeared and why they should have motivated a prolongation in 2001. I will conclude with the experimental prospects for an understanding of the Higgs mechanism in the next 50 years, and with what a discovery at LEP could have changed in this respect.