CERN boffins are growing in confidence that the particle they spotted in the latest data from their Large Hadron Collider is indeed a Higgs boson.
The Atlas experiment team has upped its level of certainty for Higgs-ness in a paper [PDF] for Physics Letters B, putting the sigma level at 5.9, which translates into a one-in-300-million chance that the observed elementary particle isn't the highly sought-after mass-giving boson.
That's well over the sigma needed to declare a discovery, which is set at 5 and represents a one-in-3.5-million chance. But the Atlas scientists aren't quite willing to settle with that because it has to narrow the mass range.
The CMS experiment team also posted a paper [PDF] with further analysis of its data, but its certainty only reached 5 sigma, around the same level reported at the start of July when the world went bonkers for the Higgs.
"The Standard Model Higgs boson is excluded at 95 per cent CL in the mass range 111–559 GeV, except for the narrow region 122–131 GeV. In this region, an excess of events with significance 5.9 sigma … is observed," Atlas said in its paper.
"Taking into account the entire mass range of the search, 110–600 GeV, the global significance of the excess is 5.1 sigma."
Announcing the discovery of the Higgs boson would have a massive impact on the physics world, and our understanding of mass, so caution is the name of the game. The CERN boffins won't want to say they've seen the Higgs until they're sure beyond, er, a shadow of a doubt.
And as physicist Paris Sphicas told The Register last month, just deciding that this is a Higgs boson isn't the end of the search: scientists are eager to learn how it fits into our universe and whether theories of supersymmetry or extra dimensions are necessary to explain how we and everything around us simply exists.
Nevertheless, upping the significance of the particle find brings us a step closer to knowing that this is a new and Higgs-like elementary particle that has never been seen before. ®