Diffractive vector meson production at COMPASS and plans for GPDs measurements

Preliminary results on the spin dependence of exclusive $\rho^{0}$ muoproduction at COMPASS are discussed. The $Q^{2}$ dependence of several spin density matrix elements and of $R = \sigma_{L}\sigma_{T}$ is presented. The data are consistent with a substantial increase of $R$ with $Q^{2}$ and a weak violation of SCHC. Next, the longitudinal double-spin asymmetry $A^{\rho}_{1}$ for $\rho^{0}$ production on polarized deuterons is shown as a function of $Q^{2}$ and $x_{Bj}$. The asymmetry is compatible with zero in the whole kinematical range. Finally, we discuss the prospects for measuring DVCS and exclusive meson production at COMPASS in order to investigate GPDs.