By Malcolm W. Browne, New York Times
August 10, 1999

The race to find an elusive but all-important particle called the Higgs boson heated up last week when Europe's most powerful accelerator reached an energy that may bring the target within range.

Because of its presumably vital importance to universal existence, the Higgs boson was dubbed "The God Particle" in the title of a book by Dr. Leon Lederman, a Nobel laureate in physics. The godlike importance ascribed to the Higgs is based on the belief that its interactions endow all the constituents of matter with mass; it is the universal giver of heft.

The hunt is on for the Higgs boson, the universal giver of heft.

To create the ephemeral Higgs in the laboratory requires a collision of two ordinary particles -- protons or electrons -- so their combined collision energy exceeds the energy of the Higgs. Last Wednesday the European Laboratory for Particle Physics (CERN) near Geneva announced it had successfully increased the energy of its 10-year-old Large Electron-Positron accelerator to 100 billion electron-volts.

The achievement means that CERN can run its LEP accelerator "flat out, during its last years of service," a spokesman said, with electrons and antielectrons hitting each other at combined energies of 200 billion electron-volts. If the lightest Higgs particle weighs less than this, it may be created and found in a matter of months.

But if the lightest Higgs is marginally heavier than this, it will be beyond the reach of the LEP accelerator, and the prize might go to CERN's major rival, the Fermi National Accelerator Laboratory at Batavia, Ill.

Fermilab recently completed a major upgrade of its Tevatron proton-antiproton accelerator that will pump far more colliding particles into its beams than was possible before. Many more collisions will occur, giving Fermilab physicists a better chance of finding the rare events expected to signal the creation and discovery of Higgs bosons.

There may be as many as five different Higgs particles working together as part of the "Higgs mechanism" -- a hypothetical system that could explain why all other particles have the masses they do. A study of the Higgs mechanism, if it is found, could also tidy up known flaws in the "Standard Model" theory, which accounts for the different types of quarks and leptons that make up all matter.

The Higgs boson is named for Dr. Peter Higgs, a Scottish theorist, who in the 1960's found hints of the particle's existence in equations describing the known constituents of matter.

No one can predict how massive the Higgs will turn out to be, except that it must be very heavy. But the lightest possible Higgs boson may weigh as little as 109 billion electron-volts -- somewhat less than the mass of an atom of silver.

If the lightest Higgs particle weighs a little more than an atom of silver, the Europeans will fail to find a Higgs in the next few months and Fermilab will have a good chance of making the discovery a little later. Dr. Lederman, a former director of Fermilab, likens the situation to a horse race.

The competition between CERN and Fermilab for the Higgs particle is reminiscent of a similar race in the 1980's for the W and Z bosons -- "vector" particles that transmit the "weak" nuclear force between other particles.

The CERN proton accelerator's energy was barely sufficient for the quest. But a Dutch physicist, Dr. Simon van der Meer, and CERN's director at the time, Dr. Carlo Rubbia, found an ingenious way to bunch colliding protons together, and the technique enabled them to snag the W and Z bosons.

Dr. Rubbia and Dr. van der Meer were awarded the 1984 Nobel Prize for their discovery. Almost certainly, a Nobel Prize also awaits the winner of the Higgs race.

But both Europe's LEP accelerator and Fermilab's Tevatron are past their prime.

Next year CERN's LEP accelerator will shut down to make way for a new accelerator, the Large Hadron Collider, which will occupy the same circular 17-mile tunnel that now holds LEP. When the new hadron collider begins operation in 2005 it will be by far the most powerful and important accelerator in the world, easily outdistancing Fermilab's capabilities.

If the current search by Fermilab and CERN for the Higgs boson turns up dry, CERN's new hadron machine will have a much better chance of finding not only the Higgs but also one or more exotic "supersymmetric" particles. Many theorists believe that for every particle known to exist there is a complementary particle that has yet to be discovered. The discovery of such a supersymmetric particle would prompt a revolution in physics.


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