Single Spin Asymmetries in Charged Pion Production from Semi-Inclusive Deep Inelastic Scattering on a Transversely Polarized ^3He Target at Q^2 = 1.4–2.7 GeV^2

Abstract

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 0.16<x<0.35 with 1.4 < Q^2 <2.7  GeV^2. 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.