Document Type


Publication Date




Publication Title

Physical Review C






035207 (12 pages)


Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive π0 electroproduction reaction γp→pπ0, expanding an analysis of the γp→nπ+ reaction from the same experiment. The results were obtained from scattering of 6-GeV longitudinally polarized electrons off longitudinally polarized protons using the CEBAF Large Acceptance Spectrometer at Jefferson Laboratory. The kinematic ranges covered are 1.1 < W < 3 GeV and 1 < Q2< 6 GeV2 . Results were obtained for about 5700 bins in W, Q2, cos(θ) , and ϕ. The beam-target asymmetries were found to generally be greater than zero, with relatively modest ϕ dependence. The target asymmetries exhibit very strong ϕ dependence, with a change in sign occurring between results at low W and high W , in contrast to π+ electroproduction. Reasonable agreement is found with phenomenological fits to previous data for W < 1.6 GeV, but significant differences are seen at higher W . When combined with cross-sectional measurements, as well as π+ observables, the present results will provide powerful constraints on nucleon resonance amplitudes at moderate and large values of Q2, for resonances with masses as high as 2.4 GeV.


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Original Publication Citation

CLAS Collaboration, Bosted, P. E., Kim, A., Adhikari, K. P., Adikaram, D., Akbar, Z., . . . Zonta, I. (2017). Target and beam-target spin asymmetries in exclusive pion electroproduction for Q² > 1 GeV². II. Ep→ eπºp. Physical Review C, 95(3), 035207. doi:10.1103/PhysRevC.95.035207


0000-0003-2243-6836 (Kuhn)

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