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 cryogenic14NH3target, and extracted double and single target spin asymmetries for ep→e′π0X in multidimensional bins in four-momentum transfer (1.0<3.2 GeV2), Bjorken-x (0.12<0.48), hadron energy fraction (0.4<0.7), transverse pion momentum (0<1.0 GeV), and azimuthal angle ϕhbetween the lepton scattering and hadron production planes. We extracted asymmetries as a function of both x and PT, which provide access to transverse-momentum distributions of longitudinally polarized quarks. The double spin asymmetries depend weakly on PT. The sin2ϕhmoments are zero within uncertainties, which is consistent with the expected suppression of the Collins fragmentation function. The observed sinϕhmoments suggest that quark gluon correlations are significant at large x.
Semi-inclusive π0target and beam-target asymmetries from 6 GeV electron scattering with CLAS
Ciullo, G.;Contalbrigo, M.;Lenisa, P.;Movsisyan, A.;
2018
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 cryogenic14NH3target, and extracted double and single target spin asymmetries for ep→e′π0X in multidimensional bins in four-momentum transfer (1.0<3.2 GeV2), Bjorken-x (0.12<0.48), hadron energy fraction (0.4<0.7), transverse pion momentum (0<1.0 GeV), and azimuthal angle ϕhbetween the lepton scattering and hadron production planes. We extracted asymmetries as a function of both x and PT, which provide access to transverse-momentum distributions of longitudinally polarized quarks. The double spin asymmetries depend weakly on PT. The sin2ϕhmoments are zero within uncertainties, which is consistent with the expected suppression of the Collins fragmentation function. The observed sinϕhmoments suggest that quark gluon correlations are significant at large x.File | Dimensione | Formato | |
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