Nucleon longitudinal spin structure at COMPASS Original Research Article

The nucleon spin structure is studied at COMPASS via the measurement of the spin dependent properties of deep inelastic muon-deuteron scattering. Both inclusive and semi- inclusive observables are investigated, with the emphasis put on the latter. This allows to access, in particular, the gluon polarization (ΔG/G) and the flavor decomposition of the quark helicity distributions. Results from measurements with longitudinal target polarization are presented, as well as uncertainties expected from the first 3 years of data taking.