Single Spin Asymmetries in Charged Pion Production from Semi-Inclusive Deep Inelastic Scattering on a Transversely Polarized He-3 Target at Q(2)=1.4-2.7 GeV2
Physical Review Letters
We report the first measurement of target single spin asymmetries in the semi-inclusive He-3(e; e' pi(+/-))X reaction on a transversely polarized target. The experiment, conducted at Jefferson Lab using a 5.9 GeV electron beam, covers a range of 0.16 < x < 0.35 with 1.4 < Q(2) < 2.7 GeV2. The Collins and Sivers moments were extracted from the azimuthal angular dependence of the measured asymmetries. The pi(+/-) Collins moments for He-3 are consistent with zero, except for the pi(+) moment at x = 0.35, which deviates from zero by 2.3 sigma. While the pi(-) Sivers moments are consistent with zero, the pi(+) Sivers moments favor negative values. The neutron results were extracted using the nucleon effective polarization and measured cross section ratios of proton to He-3, and are largely consistent with the predictions of phenomenological fits and quark model calculations.
Qian, X.; Chen, W.; Gao, H.; Katich, J.; Averett, Todd; Bradshaw, P. C.; Kelleher, A.; and Zhao, B., Single Spin Asymmetries in Charged Pion Production from Semi-Inclusive Deep Inelastic Scattering on a Transversely Polarized He-3 Target at Q(2)=1.4-2.7 GeV2 (2011). Physical Review Letters, 107(7).