The longitudinal spin structure of nucleon in semi-inclusive reactions at COMPASS.
Artem I. per la Collaborazione COMPASS
COMPASS is a fixed-target experiment located at CERN (SPS, M2 beamline). One of the important objectives of the experiment is an exploration of the longitudinal spin structure of the nucleon parametrized in terms of quark transverse-momentum--dependent parton distribution functions. This is done through studying the target spin-dependent asymmetries arising in semi-inclusive deep-inelastic-scattering reactions. For this purpose COMPASS has performed a series of semi-inclusive measurements using 160--200 GeV/c polarized muons scattering of longitudinally polarized deuteron and proton targets. In this talk selected aspects of COMPASS longitudinal spin program will be presented.