Semi-inclusive π 0 target and beam-target asymmetries from 6 GeV electron scattering with CLAS.
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 in multidimensional bins in four-momentum transfer ( GeV2), Bjorken-x (), hadron energy fraction (), transverse pion momentum ( GeV), and azimuthal angle between the lepton scattering and hadron production planes. We extracted asymmetries as a function of both x and , which provide access to transverse-momentum distributions of longitudinally polarized quarks. The double spin asymmetries depend weakly on . The moments are zero within uncertainties, which is consistent with the expected suppression of the Collins fragmentation function. The observed moments suggest that quark gluon correlations are significant at large x.
Physics Letters B
Jawalkar, S.; Koirala, S.; Avakian, H.; Bosted, P.; Griffioen, K. A.; Keith, C.; Kuhn, S. E.; Biselli, Angela; and CLAS Collaboration, "Semi-inclusive π 0 target and beam-target asymmetries from 6 GeV electron scattering with CLAS." (2018). Physics Faculty Publications. 148.
Jawalkar, S., S. Koirala, H. Avakian, P. Bosted, K. A. Griffioen, C. Keith, S. E. Kuhn, Biselli A. et al [CLAS Collaboration]. "Semi-inclusive π 0 target and beam-target asymmetries from 6 GeV electron scattering with CLAS." Physics Letters B 782, 10 (2018):662-667. https://doi.org/10.1016/j.physletb.2018.06.014