1. 2012

    CMS has discovered a new particle. No big deal, yo.

    OK, actually it is kind of a big deal. Discovering a new particle is not something that happens every day, and it’s a concrete result of having a well-tuned detector. Besides, it’s just cool. So congratulations to the CMS collaboration!

    In case you haven’t heard the story, late last week CMS announced that they had a statistically significant observation of the \({\Xi^*}_b^0\) baryon, a particle made up of an up quark, a strange quark, and a bottom quark. In this case, “statistically significant” means that they detected this particular decay signature 21 times, of which only \(3\pm 1.4\) of them can be attributed to random coincidences in the detector. So they’re about as sure as you can be in physics that they are seeing signs of a real particle. They’ve also managed to reconstruct various properties of this particle by examining the decay products, and everything matches up with the predicted properties of the \({\Xi^*}_b^0\).

    Now, why isn’t this a bigger deal, and why didn’t I write about it right away? Well, as I just mentioned, this particle was predicted to exist. Of course, the Higgs boson …