PHYSICISTS think they鈥檝e caught tantalising glimpses of the elusive particle
that gives matter its mass.
Researchers working with a giant particle detector called ALEPH at the CERN
particle physics laboratory near Geneva say a handful of oddball collisions may
mark the fleeting appearance of the Higgs boson. The Higgs is a crucial piece in
the jigsaw of fundamental particles. Finding it is currently the big prize for
particle physicists.
The machine that produced these events, the Large Electron Positron Collider
(LEP), is scheduled to close down for good at the end of this month. So the
ALEPH researchers have precious little time to collect enough data to confirm
their observation.
Advertisement
Without the Higgs boson, or some more convoluted explanation, the Universe as
we know it wouldn鈥檛 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 because
they exist only 鈥渧irtually鈥�. 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 see a Higgs, physicists have to manufacture one by smashing extremely
fast-moving particles together. The energy of the collision is converted into
matter, and if the energy is high enough a bona fide Higgs may pop into
existence. Having done so, it decays into a telltale combination of other
particles.
Such decays could account for several unusual events observed recently at
LEP, ALEPH researchers said this week at a meeting at CERN. But they admit
that their evidence is not yet conclusive. 鈥淚t鈥檚 unfortunately not enough to say
we have made a discovery,鈥� says ALEPH鈥檚 Wolf-Dieter Schlatter.
It鈥檚 possible that the events are chance combinations of random particles, or
fakes produced by familiar particles such as Z bosons decaying in just the right
way to mimic a Higgs. Such explanations are made more likely by the fact that
none of the other three particle detectors arrayed around LEP has seen any sign
of Higgs events.
The question is whether CERN should keep LEP running to try to confirm the
Higgs sighting. ALEPH researchers could double their data if LEP ran until the
end of the year.
The 27-kilometre-long LEP, housed in a ring-shaped tunnel straddling the
Swiss-French border, has already painted detailed portraits of the W and Z
bosons, and has proved that there can be no more than six quarks. 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.
In the meantime, CERN鈥檚 great rival, Fermilab near Chicago, may find the
Higgs first. Fermilab will resume colliding beam experiments this month, after
more than four years of renovation.
Some think the ALEPH team may be making too much of too little. 鈥淵ou wonder
if it鈥檚 just a way for them to extend their running time,鈥� says Dave Besson of
the University of Kansas in Lawrence. ALEPH collaborator Alan Litke rejects this
suggestion. 鈥淲e have no interest,鈥� he says, 鈥渋n running LEP for the sake of
running LEP鈥�.