Semi-inclusive π0 target and beam-target asymmetries from 6 GeV electron scattering with CLAS

Abstract 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 14 NH 3 target, and extracted double and single target spin asymmetries for e p → e ′ π 0 X in multidimensional bins in four-momentum transfer ( 1.0 Q 2 3.2 GeV 2 ), Bjorken- x ( 0.12 x 0.48 ), hadron energy fraction ( 0.4 z 0.7 ), transverse pion momentum ( 0 P T 1.0 GeV), and azimuthal angle ϕ h between the lepton scattering and hadron production planes. We extracted asymmetries as a function of both x and P T , which provide access to transverse-momentum distributions of longitudinally polarized quarks. The double spin asymmetries depend weakly on P T . The sin ⁡ 2 ϕ h moments are zero within uncertainties, which is consistent with the expected suppression of the Collins fragmentation function. The observed sin ⁡ ϕ h moments suggest that quark gluon correlations are significant at large x .