We present precision measurements of the target and beam-target spin asymmetries from neutral pion electroproduction in deep-inelastic scattering (DIS) using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. We scattered 6-GeV, longitudinally polarized electrons off longitudinally polarized protons in a cryogenic 14NH3 target, and extracted double and single target spin asymmetries for ep→e′ π0 X in multidimensional bins in four-momentum transfer (1.0 2 < 3.2 GeV2), Bjorken -x (0.12 < x < 0.48), hadron energy fraction (0.4 < z 0.7), tranverse pion meomentum (0 < PT < 1.0 GeV), and azimuthal angle ϕh between the lepton scattering and hadron production planes. We extracted asymmetries as a function of both x and PT, which provides access to transverse-momentum distributions of longitudinally polarized quarks. The double spin asymmetries depend weakly on PT. The sin 2ϕh moments are zero within uncertainties, which is consistent with the expected suppression of the Collins fragmentation function. The observed sin ϕh moments suggest that quark gluon correlations are significant at large x.

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Copyright © 2018 Elsevier Science B.V. This article first appeared in Physics Letters B 782, (July 10, 2018): 662-667. doi: 10.1016/j.physletb.2018.06.014.

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