We report the first measurement of target single spin asymmetries in the semi-inclusive 3He(e,e′π±)X reaction on a transversely polarized target. The experiment, conducted at Jefferson Lab using a 5.9 GeV electron beam, covers a range of 0.1622. The Collins and Sivers moments were extracted from the azimuthal angular dependence of the measured asymmetries. The π± Collins moments for 3He are consistent with zero, except for the π+ moment at x=0.35, which deviates from zero by 2.3σ. While the π- Sivers moments are consistent with zero, the π+ Sivers moments favor negative values. The neutron results were extracted using the nucleon effective polarization and measured cross section ratios of proton to 3He, and are largely consistent with the predictions of phenomenological fits and quark model calculations.
Qian, X.; Holmstrom, Timothy; and Jefferson Lab Hall A Collaboration, "Single Spin Asymmetries in Charged Pion Production from Semi-Inclusive Deep Inelastic Scattering on a Transversely Polarized (3)He Target at Q(2)=1.4–2.7 GeV(2)" (2011). Chemistry and Physics Faculty Publications. 20.
Phys. Rev. Lett. 107, 072003 (2011)