Scenes from a celebration: The Higgs within reach (pictures)
A behind-the-scenes look as scientists find a long-sought subatomic particle that's key to furthering humanity's understanding of the universe.
Scenes from a celebration: The Higgs within reach
Celebrating the moment: Peter Higgs congratulated by Francois Englert, from the Free University of Brussels, as researchers gathered at CERN on July 4, 2012, to hear the results of experiments in the pursuit of the long-sought Higgs boson.
Scientists now believe there are strong indications pointing to the existence of a new particle, which could be the Higgs.
More data will be needed before researchers can be certain that the particle they've discovered is the elusive Higgs boson predicted by the Standard Model. That's the theory that describes how all particles interact.
Though the results are preliminary, CERN's scientists believe the discovery likely heralds a new era in physics.
Scientists offered their conclusions after poring through data gathered from trillions of proton collisions at the Large Hadron Collider in 2011 and 2012. This was no mean feat. The LHC accelerated the protons close to the speed of light as they traversed a nearly 5-mile-long ring. In the resulting collisions, the particles created other particles -- including, they believe, the Higgs. CERN says it takes about 1 billion collisions to make a single Higgs boson.
High fives all around, but after the initial wave of excitement, scientists cautioned that there's more work to do before they can make a positive identification of the new particle's characteristics. That caveat aside, CERN researchers -- and scientists around the world -- believe they are closing in on their long-pursued grail. The strong evidence unveiled by CERN suggests that the likelihood that this observation was connected to a statistical fluctuation is less than 1 percent.
CERN particle physicists use a scale to describe the certainty of a discovery. According to CERN: "1 sigma means the results could be random fluctuations in the data, 3 sigma counts as an observation and a 5-sigma result is a discovery." CERN researchers told the assembled researchers and media that they had found "clear signs" of a new particle, at the level of 5 sigma. By the end of the month, the complete analysis is expected to be published.
A slide from the July 4 presentation. The search with the purest expected signal is done by examining events with two Z bosons that have decayed to pairs of electrons. CERN said that in the region from 120 to 130 GeV, 13 events are seen where only 5.3 were expected. Here's where probability comes in. Scientists say that the likelihood of such an excess would be three times in ten thousand if there were no new particle, according to CERN.