Update (July 4): In a press conference Wednesday morning, CERN scientists announced they have observed a new particle that bears a striking resemblance to the Higgs boson, but they stopped short of declaring a formal discovery.
"This is indeed a new particle," said experiment spokesman Joe Incandela. "We know it must be a boson and it's the heaviest boson ever found. The implications are very significant and it is precisely for this reason that we must be extremely diligent in all of our studies and cross-checks."
The researchers' results reached the 5-sigma level of certainty, strongly suggesting they have observed the elusive Higgs boson. But for now, their findings are labeled preliminary. "It's hard not to get excited by these results," said CERN research director Sergio Bertolucci. "We stated last year that in 2012 we would either find a new Higgs-like particle or exclude the existence of the Standard Model Higgs. With all the necessary caution, it looks to me that we are at a branching point: the observation of this new particle indicates the path for the future toward a more detailed understanding of what we're seeing in the data."
As CERN chief Rolf Heuer added: "We have reached a milestone in our understanding of nature. The discovery of a particle consistent with the Higgs boson opens the way to more detailed studies, requiring larger statistics, which will pin down the new particle's properties, and is likely to shed light on other mysteries of our universe."
The Higgs boson is a subatomic particle that allows other subatomic particles to have mass, making it a pretty important part of the universe — if it actually exists. Also known as the "God particle," the hypothetical speck has eluded scientists for years, raising doubts about even our most basic model of how the universe works.
But now, after decades and fortunes spent hunting it, the God particle may finally be ready to reveal itself. Scientists at the Large Hadron Collider in Europe will hold a press conference July 4 to announce big news about the boson, possibly even declaring they have formally discovered it. And while the timing on U.S. Independence Day is coincidental, it's already generating fireworks worldwide.
"We now have more than double the data we had last year," says Sergio Bertolucci of the European Organization for Nuclear Research, or CERN, in a recent press release. "That should be enough to see whether the trends we were seeing in the 2011 data are still there, or whether they've gone away. It's a very exciting time."
The search for Higgs bosons has gone increasingly well in recent months, with CERN reaching a 3-sigma level of certainty, which indicates a one-in-1,000 chance that a positive result was a fluke. Still, under the standards of modern physics, that barely counts as "strong evidence." The 5-sigma level, which has just a one-in-a-million rate of wrong conclusions, is required to call something a "discovery."
Based on the buzz ahead of CERN's July 4 event, many are speculating that point is near. "Reports from the experiments indicate [they] will reach the 5-sigma level of significance for the Higgs signal," Columbia mathematician Peter Woit writes on his blog. "So this will definitely be the long-awaited Higgs discovery announcement, and party-time for HEP [high-energy physics] physicists."
According to Nature, CERN's experiments have sigma signals ranging from 4.5 to 5, and one unidentified member of the research team is quoted as saying "without a doubt, we have a discovery." Stoking rumors even further, CERN has invited four of the earliest Higgs boson theorists to attend Wednesday's announcement, including the particle's namesake, 83-year-old British physicist Peter Higgs.
Part of Tevatron at Fermi National Accelerator Laboratory, aka Fermilab, near Chicago. (Photo: DOE)
Just in time for CERN's Fourth of July revelation, U.S. scientists are also reporting new hints of the Higgs boson this week. Researchers at Fermilab in Illinois found the evidence in data from Tevatron (pictured above), a particle accelerator built in 1983 that was shut down last year. It's not definitive, but by studying hundreds of trillions of particle collisions at Tevatron from 2001 to 2011, the researchers found data that strongly suggest the Higgs boson exists, Fermilab reported Monday.
"During its life, the Tevatron must have produced thousands of Higgs particles, if they actually exist, and it's up to us to try to find them in the data we have collected," says Luciano Ristori, a physicist at Fermilab. "We have developed sophisticated simulation and analysis programs to identify Higgs-like patterns. Still, it is easier to look for a friend's face in a sports stadium filled with 100,000 people than to search for a Higgs-like event among trillions of collisions."
Fermilab researchers saw signs of Higgs between 115 and 135 gigaelectronvolts (GeV) — 130 times the mass of a proton, and around the same search region as CERN's Large Hadron Collider. But the LHC is newer and more advanced than Tevatron, and the search will ultimately depend on it. "Our data strongly point toward the existence of the Higgs boson," says Fermilab spokesman Rob Roser, "but it will take results from the experiments at the Large Hadron Collider in Europe to establish a discovery."
A rendering from the LHC that might represent a decaying Higgs boson. (Image: CERN)
The Higgs boson may not seem like it's worth all this trouble, but it's a critical missing piece from the Standard Model of physics, an all-inclusive guide to the universe that otherwise works fairly well. The model's main flaw is that it fails to explain how certain particles have mass, such as quarks and electrons, while other particles like photons are massless. Physicists have theorized since the 1960s that subatomic mass is mediated by the "Higgs field," a force field made of Higgs bosons that treats various particles differently as they pass through.
Testing that theory requires big particle accelerators, which allow scientists to smash matter together so violently it's reduced to a cloud of subatomic wreckage. If the Higgs boson is real, it should briefly emerge at this point, existing for only a trillionth of a second before fading back into other particles. Scientists can then look for its fingerprints in data recorded by the particle accelerator.
Discovering the Higgs boson could do wonders for high-energy physics, helping explain persistent mysteries like dark matter and dark energy. But as CERN's Sergio Bertolucci tells the London Telegraph, almost any news about the Higgs boson is good news. "The important message is this: We won't know if it is the Higgs, only that it is an indication of a new state that looks like the Higgs," he says. "So this won't mark the end of a chapter but the beginning of another exciting one. For example, if we are looking for a dog and we find one that meows, that's not one discovery but two. If it's something other than the Higgs, or if there's no Higgs, then that is a win-win because we are into the realm of new physics."
To watch the July 4 announcement in real time, visit CERN's live webcast page Wednesday at 9 a.m. Geneva time (which is 3 a.m. U.S. Eastern time). And for more information about how the Higgs field is thought to work, check out this video by University of Michigan physicist Gordon Kane:
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