Transverse Target-Spin Asymmetry of Exclusive $\rho^0$ Meson Production on Proton at HERMES

Understand

Preliminary measurements are reported on the azimuthal single-spin asymmetry of exclusive rho0 mesons for a transversely polarized hydrogen target at HERMES using the 27.6 GeV HERA positron beam.

• Within the generalized parton distribution (GPD) formalism, this asymmetry is sensitive to the total angular momentum of quarks and gluons in the nucleon.
• Since the GPD formalism is only valid for mesons produced by longitudinal photons, the transverse target-spin asymmetry of longitudinal rho0 mesons is extracted assuming s-channel helicity conservation and compared to theoretical calculations.