Physicists Inch Closer to Proof of Elusive Particle

Physicists Inch Closer to Proof of Elusive Particle

By DENNIS OVERBYE
Published: July 2, 2012
Like Moses seeing the Promised Land but not being able to go there, physicists from Fermilab said Monday that its Tevatron, now shuttered but once the most powerful physics machine in the world, had fallen just short of finding a long-hypothesized particle.
Known as the Higgs boson, it explains why things in the universe have mass, and is a cornerstone of modern physics despite never being seen.

The news from the Fermi National Accelerator Laboratory added more buzz and hype about the long-sought particle as physicists and many others are standing by for an announcement on Wednesday
from CERN, the European Organization for Nuclear Research, home of the Large Hadron Collider, which supplanted the Tevatron as the big horse in physics, and whose physicists might be on the verge of announcing that they have actually found the Higgs boson.

On Monday, Fermilab, in Batavia, Ill., said its results were the best “indication” so far that the legendary particle exists.

In what amounts to a last hurrah for the Tevatron, Fermilab physicists said that when they combined the data from some 500 trillion collisions of protons and antiprotons recorded since 2001 there was a suspicious excess, a broad bump in the mass range between 115 billion electron volts and 135 billion electron volts, in the units physicists use to measure mass and energy.

The new analysis confirmed an earlier one reported last March, but with more rigor.

The odds that the Fermilab bump were due to chance were only one in 550, they said. “This is very, very low number for all practical reasons, so I have strong confidence that beautiful theory developed by theorists almost 50 years ago is indeed how the Nature works,” wrote a Fermilab physicist, Dmitri Denisov, a co-spokesman for one of the two experiments on the Tevatron, known as DZero.

Unfortunately, that is just shy of the one part in 3,000, or “3-sigma” in physics jargon, that is required to use the word “evidence,” let alone “discover,” leaving the Tevatron in its final statement unable to settle the question of the elusive boson.

Instead the stage has been cleared for CERN.

The discovery of a new fundamental constituent of nature, as the Higgs would be, is a once-in-a-generation event and the imminent discovery of the Higgs at CERN has thrown physicists into a frenzy of rumor and speculation. The five living founders of the Higgs theory have been invited to a news conference there, heightening expectations that something big is in the offing.

The boson is named for Peter Higgs of the University of Edinburgh, who was one of six physicists who envisioned a kind of cosmic molasses, now known as the Higgs field, that would impart mass to formerly massless particles trying to move through it like a celebrity trying to get to the bar. The others were Tom Kibble of Imperial College, London; Carl Hagen of the University of Rochester; Gerald Guralnik of Brown University; the late Robert Brout and Francois Englert, both of Université Libre de Bruxelles.

Physicists have been searching for the boson, a byproduct of that molasses, and the only smoking gun that it exists, since the 1970s. The search heated up last year when physicists at the Large Hadron Collider, outside Geneva, reported a bump in their data indicating a particle with a mass of about 125 billion electron volts, but that bump had about a 1 percent chance of being a fluke.

Since then the CERN collider has more than doubled the amount of data it has on the Higgs, enough perhaps to make a definitive statement.