New boson discovered, probably Higgs
Numbers are yet to be crunched and the data analysis goes on, but one thing appears to be certain: scientists at CERN have discovered a new boson, and it's probably the Higgs particle, the missing particle of the Standard Model which is thought to lend all matter its mass. Both the ATLAS and CMS experiments at CERN observe a new particle with mass between 125 and 126 GeV, comfortably within the band of possible Higgs masses previously identified.
"The results are preliminary but the 5 sigma signal at around 125 GeV we're seeing is dramatic. This is indeed a new particle. We know it must be a boson and it's the heaviest boson ever found," said Joe Incandela of the CMS experiment. "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 "5 sigma" Incandela refers to is a statement of the statistical significance of the findings. ATLAS physicist Brian Cox contextualized this on Twitter, explaining that "4 sigma roughly means that you'd expect that you're 99.99 percent certain about it," while "5 sigma is the usual particle physics threshold for discovery. It roughly means that you're 99.9999 percent sure." In this case, the "5 sigma" expresses the certainty of a new particle having been discovered.
CMS and ATLAS are separate particle detectors run by distinct research terms at the Large Hadron Collider. That they have both independently discovered the new boson is significant. However, CERN language has stopped short of declaring this an absolute discovery of the Higgs particle. Though the particle fits the description of the Higgs boson, further analysis of its properties is required.
"Positive identification of the new particle's characteristics will take considerable time and data," said a CERN press release. "But whatever form the Higgs particle takes, our knowledge of the fundamental structure of matter is about to take a major step forward."
The preliminary findings were revealed at a press conference today. Peter Higgs, who first proposed the existence of the particle, was seen in tears at the conclusion of the event, which ended with rapturous applause.
Though there's an understandable air of caution, the mood in the room could not be categorized as doubtful. "We are entering the era of Higgs measurements," said Fabiola Gianotti, head of ATLAS. CERN Director General Rolf-Dieter Heuer went further still. "I think we have it. Do you agree," he asked. Those in attendance replied enthusiastically in the affirmative.