Sivers effect in semi-inclusive deeply inelastic scattering
  The Sivers function is extracted from HERMES data on single spin asymmetries in semi-inclusive deeply inelastic scattering. Our analysis use a simple Gaussian model for the distribution of transverse parton momenta, together with the flavor dependence given by the leading 1/Nc approximation and a neglect of the Sivers antiquark distribution. We find that within the errors of the data these approximations are sufficient. 
J.C. Collins, A.V. Efremov, K. Goeke, S. Menzel, A. Metz, and P.   Schweitzer