Single-spin asymmetries in semi-inclusive pion production
  For the first time single-spin asymmetries in semi-inclusive pion production are measured by the HERMES experiment with a transversely polarised hydrogen target. Two different sine-modulations are extracted which can be related to the transversity \delta q(x) and Sivers f_{1T}^{\perp q}(x) quark distribution functions. The extracted sine-moments still contain small sub-leading twist contributions which can be extracted from HERMES data combining the results from the transversely polarised hydrogen target with previously measured results from a longitudinally polarised hydrogen target. 
U. Elschenbroich (1) (for the HERMES Collaboration) ((1) Department of   Subatomic and Radiation Physics, University of Ghen...