Michael Hoch / CERN file

The Compact Muon Solenoid, or CMS, dwarfs workers at the Large Hadron Collider during construction work in 2007. A leader of the CMS' scientific team says in a CERN video that physicists have observed a new particle that may have characteristics consistent with the Higgs boson.

A mistakenly leaked video from Europe's CERN particle-physics center reports that a new subatomic particle has been observed at the Large Hadron Collider, in the range where the long-sought Higgs boson is expected to lurk. The video has now been put into password-protected status, and CERN says viewers shouldn't "take anything for granted" until a much-anticipated seminar on the Higgs boson hunt takes place on Wednesday.

"We've observed a new particle. ... We have quite strong evidence that there's something there," Joe Incandela, spokesperson for the LHC's CMS experiment, said in the video, which was discovered by Science News on CERN's website. "So, to ascertain its properties is still going to take us a little bit of time."

Incandela said the particle has some of the characteristics associated with the Higgs boson, which plays a key role in hypotheses that explain why some subatomic particles have mass while others don't. Finding the Higgs is a key target of the $10 billion LHC project. Its discovery could open the way to new frontiers in physics, such as the study of extra dimensions and supersymmetry.

Consistent with the Higgs
The physicist said that the particle decayed into two photons, in a way consistent with Higgs' behavior. He also said it's 130 times as massive as a proton — which is within the expected mass range for the Higgs.

"This is very significant," said Incandela, a physicist from the University of California at Santa Barbara who was the first U.S. scientist to be elected spokesperson for an LHC experiment. "This is the most massive such particle that exists, if we confirm all of this, which I think we will. ... This is something that may, in the end, be one of the biggest discoveries, or observations, of any new phenomena that we've had in our field in the last 30 or 40 years, going way back to the discovery of quarks."

If the particle's characteristics correspond to the predictions provided by some of the theories on the frontier of physics, "then we're really seeing something very, very closely tied to the  fabric of space and time, something that's really fundamental to the universe, and that represents a major discovery, perhaps as big as the discovery of quarks, perhaps as big as the discovery of antimatter," Incandela said.

Incandela characterized the CMS team's find as "very strong evidence," but he downplayed the use of the word "discovery" — a word that physicists reserve only for the most solid findings, with only one chance out of 3 million that the result is a statistical fluke. Instead, he emphasized the term "observation," which he said means that the particle is "definitely there, and it's very unlikely to go away."

He said the particle could be the kind of Higgs boson that fits perfectly with the existing theory of particle physics, the Standard Model, or it could be an unorthodox type of particle that doesn't fit the model. "If that's the case, then we have something really profound here," he said. "It could be a gateway to the next phase of exploring the deepest parts of the fabric of our universe."

He emphasized that CMS' results were only preliminary, and did not refer to any claims from the ATLAS collaboration, the other team most heavily involved in the search for the Higgs. But he did say he expected the results to be sufficiently confirmed to lead to a scientific publication by the end of July.

"We're very excited," Incandela said.

A tipoff? Or a red herring?
The video, which was dated July 4, appeared to provide a tipoff to the announcement planned for Wednesday. Incandela's comments reflected what the pre-announcement buzz has been: that the CMS and ATLAS teams observed an anomalous particle with the characteristics of the Higgs, with a confidence level close to that required to claim a discovery. 

However, this was just one video interview with one senior researcher, and it's not clear how much the video will reflect what the team leaders will say at the seminar. When the video came to light, outside physicists cautioned that the full story may turn out to be different.

"Really, we need to see ATLAS and CMS data side by side, e.g., are peaks in the same places?" theoretical physicist Robert Garisto, an editor at Physical Review Letters, told me in a Twitter conversation. On the other hand, he said, "I wouldn't bet against the Higgs now."

CERN spokesman James Gillies struck a similar note of caution. He told me today that the Incandela interview was "one of several videos that we recorded to cover all the bases." CERN tried to keep all of the advance videos password-protected, to guard against premature release, but "one of them became visible for a short period of time ... we don't know why."

The ATLAS and CMS teams, from their spokespersons on down, are trying to abide by Wednesday's embargo on their findings.

"Until the seminar tomorrow, don't take anything for granted," Gillies told me. You can watch CERN's webcast of the particle-physics fireworks beginning at 3 a.m. ET.

Update for 2:30 p.m. ET: Credit for spotting the video on the CERN website goes to Science News' Kate Travis.

Previous episodes in the Higgs hunt:

• Has Higgs been found? Almost
• How the Higgs gives things mass
• Higgs boson hits new highs
• Ups and downs for Higgs boson buzz
• Cartoons visualize the Higgs boson
• Can physicists crack the big puzzle?
• Flash graphic: Inside the Big Bang Machine
• Flash graphic: Michio Kaku on LHC nightmares and dreams
• Msnbc.com's special report on the Large Hadron Collider

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.