Physicists are closing in on an elusive subatomic particle that, if found, would confirm a long-held understanding about why matter has mass and how the universe's fundamental building blocks behave.
Few people outside physics can fully comprehend the search for the Higgs boson, which was first hypothesized 40 years ago. But proving that the "God particle" actually exists would be "a vindication of the equations we've been using all these years," said one Nobel laureate.
Scientists announced Tuesday that they had found hints but no definitive proof of the particle that is believed to be a basic component of the universe. They hope to determine whether it exists by next year.
It's hard to find, not because it is especially tiny, but because it is hard to create, said physicist Howard Gordon of the Brookhaven National Laboratory in Upton, New York. He works with the ATLAS experiment, one of two independent teams looking for the Higgs boson at CERN, the European Organization for Nuclear Research near Geneva.
CERN runs the Large Hadron Collider under the Swiss-French border, a 17-mile (27-kilometer) tunnel where high-energy beams of protons are sent crashing into each other at incredible speeds.
A fraction of those collisions could produce the Higgs particle, assuming it exists.
Researchers said Tuesday that they had defined a range of likely masses for the Higgs.
CERN's director-general, Rolf Heuer, said "the window for the Higgs mass gets smaller and smaller" as scientists learn more.
"But be careful _ it's intriguing hints," he said. "We have not found it yet. We have not excluded it yet."
Tuesday's revelations were highly anticipated by thousands of researchers, but the ideas behind the Higgs boson date back to the 1960s.
British physicist Peter Higgs and others theorized its existence to explain why the fundamental particles in matter have mass. Those particles, such as electrons, are the building blocks of the universe. Mass is a trait that combines with gravity to give an object weight.
Frank Wilczek, a Nobel laureate and physics professor at the Massachusetts Institute of Technology, said finding the Higgs boson would tie up a loose end of the standard model of physics, which requires that a Higgs-like particle exist.
"Since the equations have worked so brilliantly now for decades, it's really nice to dot the i's and cross the t's," Wilczek said.
In addition, if the mass of the Higgs is within a certain range, that would support some other theories that go beyond the standard model, he said.
Those theories predict the existence of other yet-to-be-found particles, meaning the Large Hadron Collider "will have another wave of brilliant discoveries in the future," Wilczek said.
The mass range reported Tuesday is "perfect" to meet that requirement, he said.
"Because it fits together so beautifully with everything else we know ... I'm certainly inclined to believe it," he said. He called Tuesday's presentations "awesome ... just beautiful work."
The lead physicist for the team running the separate CMS experiment outlined findings similar to those of the ATLAS team. The collaborations for the ATLAS and CMS experiments each involve about 3,000 scientists and engineers.
Associated Press Writer Malcolm Ritter in New York contributed to this report.