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past feature
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On the Origins of
Mass
Scientists working
at the Large Electron Positron Collider
(LEP) at the CERN particle physics
laboratory near Geneva may have detected
the elusive Higgs boson. The Higgs is a
big prize for particle physicists since
without it, or some more convoluted
explanation, the Universe as we know it
wouldn't exist.
Postulated more than 30 years ago, the
Higgs gives particles such as quarks and
electrons their mass. Particles swim
through a sea of hidden Higgs bosons,
which drag on them and produce inertia,
the essence of mass.
Physicists have been searching for the
Higgs for more than a decade. Although
Higgs particles are extremely massive,
they are normally hard to spot. Higgs
particles exploit the inherent uncertainty
in quantum mechanics to pop in and out of
existence for only the briefest of
instants, too short a time to be
observed.
To detect a Higgs, physicists collide
extremely fast-moving particles together.
The energy from the collision is converted
into matter, and if the energy is high
enough a Higgs boson may appear. On doing
so, it decays into a telltale combination
of other particles.
Such decays could account for several
unusual events observed recently at LEP,
researchers said this week at a meeting at
CERN. But they admit that their evidence
is not yet conclusive. "It's unfortunately
not enough to say we have made a
discovery," says Dr. Wolf-Dieter
Schlatter. It is possible that the events
are chance combinations of particles, or
indistinguishable particles such as Z
bosons decaying in just the right way to
mimic a Higgs.
The 27km LEP, housed in a ring-shaped
tunnel straddling the Swiss-French border,
has already painted detailed portraits of
the W and Z bosons. But it is due to be
dismantled to make way for a new machine
in the same tunnel, the Large Hadron
Collider, scheduled to begin hunting for
the Higgs particle in 2005.
The full article appears in the September
11 issue of New
Scientist.
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