Hard Electroproduction of Photons and Mesons on the Nucleon

The $\gamma$, ${\pi }^0$, and ${\rho }_L^0$ electroproduction reactions are studied in the Bjorken regime. They are sensitive to the recently introduced off-forward parton distributions. A factorized model for these distributions is shown to be able to interpret the few existing ${\rho }_L^0$ data. Calculations are given in different kinematics and experimental perspectives are discussed.