Spin structure of exclusive ω muoproduction at COMPASS

Spin Density Matrix Elements (SDMEs) are determined for exclusive ω meson production on unpolarized protons, in the COMPASS kinematic region of 1.0 (GeV/c)2 < Q 2 < 10.0 (GeV/c)2, 5.0 GeV/c2 < W < 17.0 GeV/c 2 and . Using extracted the preliminary SDMEs values the hypothesis of S-Channel Helicity Conservation (SCHC) is studied. Certain matrix elements that correspond to the transition indicate violation of SCHC in exclusive ω production. A sizable contribution of unnatural parity exchange amplitudes is found for exclusive ω meson muoproduction, and there is a clear indication of its decrease with increasing W. The extracted longitudinal-to-transverse cross section ratio is 0.553 ± 0.044 ± 0.020.