When nucleons bind to form a nucleus, does each nucleon "retain ownership" over its quarks (is each nucleon a truly unique entity)? Or is it possible for quarks to swap from one nucleon to another? Or does it not make sense to talk so exactly about them?

One unique concept that is exclusively found in quantum field theory, which describes the process you're talking about, is that all particles of the same type are indistinguishable. So, if it did happen, we wouldn't be capable of detecting it necessarily. But what we probably can do is calculate some scattering cross-sections between quark trios making use of the known properties of nucleons. My understanding is that the scale on which quarks interact with other quarks is dramatically smaller than even the scale on which nucleons interact. This would suggest that, QFT indistinguishability aside, energetically there probably isn't any exchange of quarks among bound nucleons.

I'm a chemical physicist whose background is statistical mechanics, so this isn't my specialty at all. If this doesn't make sense, feel free to correct me if you're in the know on the topic.

/r/askscience Thread