Measurement of single-spin azimuthal asymmetries in semi-inclusive electroproduction of pions and kaons on a longitudinally polarised deuterium target

Abstract Single-spin asymmetries have been measured for semi-inclusive electroproduction of π + , π − , π 0 and K + mesons in deep-inelastic scattering off a longitudinally polarised deuterium target. The asymmetries appear in the distribution of the hadrons in the azimuthal angle φ around the virtual photon direction, relative to the lepton scattering plane. The corresponding analysing powers in the sin φ moment of the cross section are 0.012±0.002(stat.)±0.002(syst.) for π + , 0.006±0.003(stat.)±0.002(syst.) for π − , 0.021±0.005(stat.)±0.003(syst.) for π 0 and 0.013±0.006(stat.)±0.003(syst.) for K + . The sin2 φ moments are compatible with zero for all particles.