At CERN (Geneve) the experimental run of the LEP was extended.
It was originally planned to conclude LEP's eleven year
period of physics research at the end of september,
and to begin the complex operations for the installation of
the LHC (Large Hadron Collider). However, exciting new results
from the LEP experiments justify this change.
LEP's main physics aim has been to search for the missing
link of the standard model of particle physics: the Higgs boson.
The Higgs mechanism is part of the standard model and
allows particles to have non-zero mass. Its central concept is
a field that pervades the whole of space. Particles that interact
with the Higgs field have mass, and their masses are determined
by the strength of their interaction with the field. The Higgs boson is
the particle associated with the oscillation of the Higgs field.
Excellent work by the CERN teams has allowed the LEP
accelerator to achieve energies up to 210 GeV, well beyond
the original design energy. Significant experimental data started
to be accumulated and a number of events compatible (3 standard
deviations) with a Higgs boson production with mass around 115 GeV
was reported in the results of the LEP experiments. However these
events are also compatible with originating from other processes.
As a consequence it is at present impossible either to confirm the
existence of a 115 GeV Higgs boson.
Higgs boson candidates (pictures)
http://alephwww.cern.ch/ALPUB/seminar/wds/dali.html
http://press.web.cern.ch/Press/Releases00/Hqq2000_Delphi.jpg
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