Photoproduction of omega with linearly polarized photons at CLAS

The CLAS-g8 running period with linearly polarized photons allowed for the extracton of beam and parity asymmetry for the $\omega p$ channel at photon energies between threshold and 2.1 GeV. Although our analysis aims for providing tight constraints on baryon resonances decaying into $\omega N$, a by-product is the separation of contributions of natural and unnatural parity- exchange mechanisms. Such a measurement is considered as an important step to parametrize the t-channel background for resonant production. The vector meson is identified in the decay mode $\omega\to\pi^+\pi^-\pi^0$. The recoil proton was detected in coincidence with two charged pions and the missing $\pi^0$ identified via missing mass. The three-pion mass spectrum shows a strong $\omega$ signal that is enhanced in the forward direction as expected from diffractive and pion-exchange processes. The extracted spin density matrix elements confirm the dominating pion-exchange mechanism for the lower energy points. However, the (preliminary) cross section and asymmetries are not fully consistent with t-channel processes: the cross section enhancement at $\cos\theta_{cm}\simeq 90^\circ$ and the modulation of the angular distribution of the decay pions indicate the presence of resonant production.