Flavor decomposition of the nucleon form factor $F_1$ at very large momentum transfer

At large momentum transfer dominance of the Sachs magnetic form factor, GM, in the Dirac form factor, $F_1$, allows determination of the $F_1$ flavor structure of the nucleon from the measurement of the cross section ratio of the D(e,e'n) and D(e,e'p) reactions. We will present an analysis of the range of momentum transfer up to 18 GeV$^2$ which could be experimentally accessed at JLab Hall A with the future experiments. A potential zero crossing of the down quark contribution to the proton $F_1$ would be discussed in the framework of the GPDs.