The Proton Electromagnetic Form Factor $F_2$ and Quark Orbital Angular Momentum

We analyze the proton electromagnetic form factor ratio $R(Q^2)=Q{F}_2(Q^2)\mathrm{/}{F}_1(Q^2)$ as a function of momentum transfer $Q^2$ within perturbative QCD. We find that the prediction for $R(Q^2)$ at large momentum transfer $Q$ depends on the exclusive quark wave functions, which are unknown. For a wide range of wave functions we find that $ QF_2/F_1 \sim
const$ at large momentum transfer, in agreement with recent JLAB data.