Earlier this month, I came across a healthy number of articles on the observation at Fermilab of a single top quark, produced by interactions involving the weak nuclear force. As a scientist who dabbled in particle physics in graduate school, I still like to see what’s going in that field (if enough people ask, I may share the story of why I left particle physics). The top quark, the heaviest of the set of six quarks, is typically produced in quark/anti-quark pairs via the strong nuclear force. The production of a single top is a much rarer event and, although predicted theoretically, was very difficult to see and a great achievement.
I was surprised this week, though, to see (via StumbleUpon) that Fermilab has made another, potentially more significant discovery: an unpredicted resonance with a mass of 4140 MeV (mega-electron volts). I use the term “resonance” to describe an extremely short-lived “particle” which rapidly decays into other, less massive, components. This particle has been named “Y(4140)”, for lack of better description. Dorigo at A Quantum Diaries Survivor has a good description of the physics.
The interesting thing about this discovery is that it is previously unpredicted “particle”. Presumably it is still made of some combination of fundamental quarks and anti-quarks, but it is a combination which hasn’t been seen before, and the exact composition is still unknown. The thing is, I haven’t seen much talk about Y(4140), in the press or the blogs. Though the single top quark discovery was a monumental and significant achievement, I would have thought that Y(4140) would have garnered more attention.
Is there some reason I haven’t heard more about this? Are unknown hadron resonances more common than I realize? Am I just not reading the right physics blogs? Any particle physicists want to weigh in?