Collins effect and single spin azimuthal asymmetriesin the HERMES and COMPASS experiments

Predictions are made for single spin azimuthal asymmetries due to the Collins effect in pion production from semi-inclusive deeply inelastic scattering off transversely and longitudinally polarized targets for the HERMES and COMPASS experiments. The x-dependence of the asymmetries is evaluated using the parton distribution functions from the chiral quark-soliton model. The overall normalization of the predicted asymmetries is determined by the information on the Collins fragmentation function extracted from previous HERMES data on azimuthal asymmetries from a longitudinally polarized target. The single spin asymmetries from the transversely polarized proton target are found to be about 20% for positive and neutral pions both at HERMES and COMPASS. For a longitudinally polarized target we obtain for COMPASS a sin(phi) asymmetry of 1% and a sin(2phi) asymmetry of about 3%.
10 pages, 9 figures, Ref.[29] added