Discovery of charm quark,
Pls add more ...
An amazing coincidence is that the reduced decay rate of J/Psi (the decay rate divided by the cube of its mass) coincides with the one of the pion, which is a spin zero composite. This is an unexplored result.
As for your original question: understanding of QCD
Well, I konw we understand QCD better. But could a few specific items be listed, sort of?
Separate names with a comma.