Amplitudes ratios in $\rho^0$ leptoproductions and GPDs
  We investigate exclusive leptoproduction of $\rho^0$ meson. These reactions were analyzed within the factorizing handbag approach. In our model good agreement of observables for light meson production with experimental data in a wide energy range was found.   Using the model results we calculate the ratio of different helicity amplitudes for a transversely polarized proton target to the leading twist longitudinal amplitude. Our results are close to the amplitude ratios measured by HERMES. 
S.V. Goloskokov
hep-ph