Beam-Spin Asymmetries in the Azimuthal Distribution of Pion Electroproduction

The collaboration
Phys.Lett.B 648 (2007) 164-170, 2007.

Abstract (data abstract)
DESY-HERA. Measurement of the beam-spin asymmetry (SSA) in the azimuthal distributions of pions produced in semi-inclusive deep-inelastic scattering of 27.6 GeV polarized positrons from a hydrogen gas target. The sinusoidal amplitudes of the asymmetry on the angle phi of the hadron production plane around the virtual photon direction relative to the lepton scattering plane is measured for both charged and neutral pions.