Vacuum Polarization and the Quark-Parton Puzzle

We suggest a solution to the question of why isolated quark-partons are not observed. It is argued that gauge theories can have the light-cone behavior of quark fields without quark production in deep-inelastic reactions. Our ideas are illustrated in the exact solution of quantum electrodynamics in one space and one time dimension. The theory's crucial physical property is the extreme polarizability of its vacuum. Predictions for deep inelastic final states are presented.