# In inelastic scattering does the exchange photon interact with sea quarks?

In deep inelastic scattering between electon and proton, the electron emits a photon that interacts with a quark of the proton, which absorbs it. Then, in a second time, the quark interacts with the others in the hadronization process and new particles can be formed.

I can't understand if the quark involved in the scattering (that absorb energy from the exchange photon) must be a valence quark or can also be a sea quark.

In other words, does the exchange photon "see" the sea quarks and interact also with them or only the valence quarks are physically involved in the scattering?

A large virtuality momentum transfer $Q$ provided by the interacting probe (typically a photon for neutral current DIS as mentioned) means it can resolve length scales $\sim 1/Q$. This is just a consequence of the HUP. So, as $Q$ gets large you can resolve smaller and smaller length scales and thus start to see the parton sea soup structure of the hadronic target, i.e. the proton. Originating in Regge theory, this pushes us into the domain of small $x$, where the sea gluon distribution is dominant. Indeed, the sea partons partake in the hard scattering not just the valence up and down.