Exclusive meson production at HERMES

The exclusive electroproduction of pseudoscalar and vector mesons was studied with the HERMES spectrometer at the DESY laboratory by scattering 27.6 CeV positron and electron beams off a transversely polarized hydrogen target The results are compared to calculations based on generalized parton distributions; some of which are sensitive to the contribution of the total angular momentum of the quarks to the proton spin