When CERN announced the discovery of a new particle last week, it was very, very careful to not explicitly call that particle the Higgs boson, instead citing "strong evidence" for the discovery of "a particle consistent with the Higgs boson." Now we know why: a new analysis suggests that CERN's data may show an "impostor" particle, and not the Higgs.
The way that the Large Hadron Collider finds new particles isn't by observing the particles themselves, which (in the case of the Higgs) don't last long enough to be detected directly. Instead, the LHC detects all of the stuff that the Higgs decays into. Of course, lots of other things decay into that stuff, too, so you have to run experiments over and over again to gain statistical confidence that you're looking at something new and not just a combination of things that you've seen before. We've got more info on that process here.
What CERN announced last week was the discovery of a new particle in the correct mass range to be the Higgs, but further analysis of the data from particle physicists at Argonne National Laboratory in Illinois suggests that CERN is just about as likely to have found evidence for more exotic varieties of the Higgs particle, called Higgs doublets or Higgs triplets. These "impostor" Higgs particles are part of a non-Standard Model interpretation of the Higgs concept, where a bunch of different Higgs-type particles (instead of just one) are together responsible for the Higgs field.
Based on the data that CERN has presented so far, the researchers found that statistically speaking, "a generic Higgs doublet and a triplet imposter give equally good ﬁts to the measured event rates" that CERN suggests are evidence for the more traditional Higgs boson. In fact, while the Standard Model Higgs does make for a slightly better fit to the data overall, one statistical measure does put the triplet impostor ahead.
While it seems most likely (at least by a little bit) that we are looking at the Higgs and not something stranger, the point here is that CERN doesn't know a whole lot about what's going on quite yet.
There's something new out there, and it could definitely be the Higgs boson, but it's going to take a lot more work before we're able to find definitive proof. And in the mean time, there's still a realistic chance that the Higgs (or whatever this is) could turn out to be way, way crazier than we ever though it would be.