I recently read a question about whether photons, electrons, neutrinos... are a part of the proton since there are these sea-quarks he learned about. And the answers were confusing to me because the most of them stated that
Since the sea-quarks and also the electrons and positrons are virual particles there are no real positrons or electrons inside the proton, which could be observed.
My question is, what about the deep inelastic scattering? Isnt there a chance to scatter on a strange quark for example when colliding a proton and a electron, since a part of the four-momentum of the proton is carried by a strange quark? And isnt that a observation of a sea-quark ?