New Particle Could Signal End of Standard Model

There has been a lot of excitement in the particle physics world lately. Tevatron, the particle accelerator in the US, may have discovered a new particle. Readings taken from the accelerator have shown a bump in one of the graphs, indicating an excess of particle collisions within that specific mass range. The exciting thing is that a bump like this one is often associated with the existence of a particle. But that's not all. If this is the discovery of a new particle, then it is a totally unexpected one, in a mass range where no one predicted the existence of anything.

The reason for this is due to the Standard Model of Particle Physics, the current theory that all fundamental particle physics are based on. Although the model has been added to and adapted over the past century or so, the main theory was finalized in 1974, and since then particle physicists have been working to find the particles that the theory says should exist, but just haven't been found yet. That includes the search for the Higgs boson, the particle that would finish off the Standard Model if/when it is found.

However, this new finding is clearly not the Higgs boson — there is no way it can be. It's in the wrong mass range. In fact, the Standard Model as it exists at the moment has no space for this new particle at all.

But the finding still needs to be confirmed. At the moment, the significance of the readings (i.e., the likelihood that the particle does exist) is at the three sigma level. This means there is about a tenth of a percent chance that the bump was caused by a statistical anomaly. A discovery can only be verified at a five sigma level (i.e., when there is a millionth of a percent chance that the bump was a fluke).

Basically, more data is needed to confirm or deny the finding. But we won't have to wait long for that. The data already exists, it just needs to be analysed at this newest point. If the bump becomes more prominent with the addition of the new data, then we have a new particle; if the bump gets smaller or less pronounced, then we don't.

But even if it isn't a new particle and it is just a bump, this is still a discovery in and of itself. The excess of collisions being picked up as a bump have to be caused by something, most likely a greater than normal number of collisions from other particles. If this is the case, then the theory that predicts this number is wrong. The calculations made to generate these numbers are all based on the theories that have been used for decades. They are considered reliable and well understood. If they are wrong, then this would mean a total rewrite of physics textbooks everywhere.

Either way, this really could be the discovery of the century for particle physics, and strangely enough, it has nothing to do with the Higgs boson.

Image Credit: Reidar Hahn (via Wikimedia)