Beam asymmetry in near threshold omega photoproduction off the proton

The photoproduction of omega mesons off protons has been studied at the Bonn ELSA accelerator from threshold to E_gamma = 1700 MeV. Linearly polarized beams were produced via coherent bremsstrahlung. Large photon asymmtries in excess of 50% were obtained, whereas the pion asymmetries from omega \to pi^0 gamma are close to zero. The asymmetries do characteristically depend on Theta_{cm} rather than |t| and indicate s-channel resonance formation on top of t-channel exchange processes.