Physicists investigating the makeup of the universe say they are closing in on the long-sought but elusive Higgs boson, a particle they believe was key to turning debris from the big bang into stars, planets and finally life.
The researchers spoke after the Fermi National Accelerator Laboratory in Illinois, also known as Fermilab, reported that it had spotted likely signs of the particle. Europe's CERN research center saw similar signals late last year.
"The endgame is approaching in the hunt for the Higgs boson," said Jim Siegrist, associate director for High Energy Physics at the Department of Energy in Washington, which oversees Fermilab operations.
"It is good to see all the signs lining up," said CERN spokesman James Gillies, while Oliver Buechmueller of the center's CMS experiment said: "It seems we are getting closer and closer ... this summer is going to be very hot."
But they all insisted it was much too early to claim a formal discovery, which would fill in the last major gap in the so-called Standard Model of particle physics that has underpinned science's view of the cosmos for 40 years.
Existence of the boson, and its linked particle field, was posited in 1964 by British physicist Peter Higgs, who argued that a mechanism must exist to turn matter into mass after the primeval explosion that created the universe 13.7 billion years ago.
The search began in earnest only in the 1980s, first in Fermilab's Tevatron particle collider and later in a similar machine at CERN, but most intensively since 2010 with the start-up of the European center's Large Hadron Collider.
Tantalizing glimpses
In December last year, after only 18 months of operations, the teams behind the CMS detector and another experiment at the LHC, known as ATLAS, reported "tantalizing glimpses" of what could well be the Higgs in the product of tens of millions of particle collisions in the collider.
The collisions, at a tiny fraction under the speed of light, re-create in miniature the type of events that occurred immediately after the Big Bang, all monitored and recorded by computers.
The latest turn in the Higgs saga came at an annual scientific gathering, the Moriond Conference, in the Italian Alpine ski resort of La Thuile with scientists from the Tevatron coming up with near-final measurements from their machine.
These, emerging from study of the recordings of the final collisions in the Tevatron before it was closed down last September, showed Higgs-like phenomena in the same energy range as the LHC, 115 to 130 gigaelectron-volts (GeV).
Italian researcher and blogger Tomasso Dorigo, who works with both CERN and Fermilab, said the independent but similar results from differing experiments "does raise the odds to which I am willing to bet that the Higgs is there."
Pauline Gagnon, a scientist with the ATLAS team at CERN who is attending the Moriond meeting, provided a vivid illustration of what the latest information means.
"This is a bit like seeing the first pimples when a child develops chicken pox. Until she is covered with them, despite some early tell-tale signs, it is too early for a definitive diagnosis," she wrote on her blog.
Scientists are now looking to the next few months at the subterranean LHC — in which during a winter break engineers have sharply boosted the total collision energy — to come up with conclusive proof that Peter Higgs, now 82, was right.
The giant circular machine, the largest single scientific experiment ever mounted, is expected to start running again in mid-March and stay in operation until November. "The excitement is mounting," said Buechmueller.
Additional reporting by Reuters' Andrew Stern in Chicago.