Found - charm quark in proton (and an anticharm). Quantum mechanics is already quite sufficiently bizarre, this is just piling on.


Diamond Member
May 15, 2015
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A very charming proton

But in quantum mechanics, a particle’s structure is governed by probabilities, meaning there is theoretically a chance that other quarks could crop up inside the proton in the form of matter-antimatter pairs. An experiment at the European Muon Collaboration at CERN in 1980 hinted the proton might contain a charm quark and its antimatter equivalent, an anticharm, but the results were inconclusive and hotly debated.

There were further attempts to identify the proton’s charm component, but different groups found conflicting results and had difficulty separating out the intrinsic building blocks of a proton from the high energy environment of particle accelerators, where every kind of quark is created and destroyed in rapid succession.

Now, Juan Rojo at Vrije University Amsterdam in the Netherlands and his colleagues have found evidence that a small part of the proton’s momentum, around 0.5 per cent, comes from the charm quark. “It’s remarkable that even after all these decades of study, we’re still finding new properties of the proton and, in particular, new constituents,” says Rojo.