On April 6th, the CDF collaboration reported an anomaly observed in proton anti-proton collision events which produced a W boson and two sprays of particles called “jets”.  The analysis analyzes events containing one lepton (electron or muon), missing momentum perpendicular to the nominal proton beam axis from an escaping neutrino, and two jets whose energies are measured in the calorimeter. In these events, the two-jet invariant mass shows a small excess of events over a steeply falling background distribution. The challenge with this measurement is understanding the shape of the background very well.  There is a mood of guarded excitement in the community because of the possibility that this excess might be due to a new particle never before observed, and not predicted by the Standard Model of particle physics.

The New York Times article is interesting, as is the post to the arXiv.  The question on everyone’s mind is, “Is this real?” The analysis uses only about half of the Tevatron Run II data, and in principle the other Tevatron detector collaboration, D0, should be able to see this too if it is real, as should the LHC experiments ATLAS and CMS once they have enough data.  There will definately be another chapter to this story once more data is analyzed and D0 and the LHC experiments weigh in.