Measurement of double polarisation asymmetries in ω -photoproduction

H. Eberhardt, T.C. Jude, H. Schmieden, A.V. Anisovich, B. Bantes, D. Bayadilov, R. Beck, Yu. Beloglazov, M. Bichow, S. Böse, K.-Th. Brinkmann, Th. Challand (+63 others)
2015 Physics Letters B  
The first measurements of the beam-target-helicity-asymmetries E and G in the photoproduction of ω-mesons off protons at the CBELSA/TAPS experiment are reported. E (G) was measured using circularly (linearly) polarised photons and a longitudinally polarised target. E was measured over the photon energy range from close to threshold (E_γ = 1108 MeV) to E_γ = 2300 MeV and G at a single energy interval of 1108 < E_γ <1300 MeV. Both measurements cover the full solid angle. The observables E and G
more » ... servables E and G are highly sensitive to the contribution of baryon resonances, with E acting as a helicity filter in the s-channel. The new results indicate significant s-channel resonance contributions together with contributions from t-channel exchange processes. A partial wave analysis reveals strong contributions from the partial waves with spin-parity J^P=3/2^+, 5/2^+, and 3/2^-.
doi:10.1016/j.physletb.2015.09.049 fatcat:kwya22qr7zg5lkblzanrbx2fte