Single Spin Asymmetries in Charged Kaon Production from Semi-Inclusive   Deep Inelastic Scattering on a Transversely Polarized $^3{\rm{He}}$ Target
  We report the first measurement of target single spin asymmetries of charged kaons produced in semi-inclusive deep inelastic scattering of electrons off a transversely polarized $^3{\rm{He}}$ target. Both the Collins and Sivers moments, which are related to the nucleon transversity and Sivers distributions, respectively, are extracted over the kinematic range of 0.1$<$$x_{bj}$$<$0.4 for $K^{+}$ and $K^{-}$ production. While the Collins and Sivers moments for $K^{+}$ are consistent with zero within the experimental uncertainties, both moments for $K^{-}$ favor negative values. The Sivers moments are compared to the theoretical prediction from a phenomenological fit to the world data. While the $K^{+}$ Sivers moments are consistent with the prediction, the $K^{-}$ results differ from the prediction at the 2-sigma level. 
Y. X. Zhao, Y. Wang, K. Allada, K. Aniol, J.R.M. Annand, T. Averett,   F. Benmokhtar, W. Bertozzi, P.C. Bradshaw, P. Bosted,...
nucl-ex