Transverse target spin asymmetries in exclusive ρ0ρ0 muoproduction

Exclusive production of ρ0ρ0 mesons was studied at the COMPASS experiment by scattering 160 GeV/c160 GeV/c muons off transversely polarised protons. Five single-spin and three double-spin azimuthal asymmetries were measured as a function of Q2Q2, xBjxBj, or pT2. The sinϕS asymmetry is found to be −0.019±0.008(stat.)±0.003(syst.)−0.019±0.008(stat.)±0.003(syst.). All other asymmetries are also found to be of small magnitude and consistent with zero within experimental uncertainties. Very recent calculations using a GPD-based model agree well with the present results. The data is interpreted as evidence for the existence of chiral-odd, transverse generalized parton distributions.