Spin effects in exclusive $\rho^{0}$ meson production at COMPASS experiment

Preliminary results from exclusive production of $\rho^{0}$ mesons at the COMPASS experiment at CERN, using a 160 GeV polarized muon beam and a large polarized nuclear target, are presented. The studied reaction is exclusive $incoherent \rho^{0}$ production, $\mu N\rightarrow\mu N\rho^{0}$, with $N$ being the nucleon in any of the nuclei of the target. The measurements were done in a wide range of $Q^{2}$: 0.01 $< Q^{2} <$ 10 GeV$^{2}$, at $\langle W \rangle\approx$ 10 GeV. The results for $r^{04}_{00}, r^{1}_{1 -1}$ and Im $r^{3}_{1 -1}\rho^{0}$ spin density matrix elements and the ratio $R = \sigma_{L}/\sigma_{T}$, based on 700 000 events selected from 2002 data, are shown and commented.