Hard Exclusive \rho^0-Meson Production at COMPASS

Abstract

New results for the transverse target spin azimuthal asymmetry A_{UT}^{sin(\phi-\phi_S)} for hard exclusive \rho^0-meson production on a transversely polarised ^6LiD and NH_3 target will be presented. The measurement was performed with the COMPASS detector using the 160 GeV/c muon beam of the SPS at CERN. The asymmetry is sensitive to the nucleon helicity-flip generalised parton distribution E, which is related to the orbital angular momentum of quarks in the nucleon.Comment: To appear in the proceedings of 20th International Workshop on Deep-Inelastic Scattering and Related Subjects (DIS 2012), Bonn, 26-30 March 201