Document Type
Article
Department/Program
Physics
Journal Title
PHYSICAL REVIEW C
Pub Date
3-20-2017
Volume
95
Issue
3
Abstract
Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive pi(+) electroproduction reaction. gamma(*) p -> n pi(+). 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 range covered is 1.1 < W < 3 GeV and 1 < Q(2) < 6 GeV2. Results were obtained for about 6000 bins in W, Q(2), cos(theta(*)), and phi(*). Except at forward angles, very large target-spin asymmetries are observed over the entire W region. Reasonable agreement is found with phenomenological fits to previous data for W < 1.6 GeV, but very large differences are seen at higher values of W. A generalized parton distributions (GPD)-based model is in poor agreement with the data. When combined with cross-sectional measurements, the present results provide powerful constraints on nucleon resonance amplitudes at moderate and large values of Q(2), for resonances with masses as high as 2.4 GeV.
Recommended Citation
Bosted, P. E.; (…); Griffioen, Keith A.; and et al., Target and beam-target spin asymmetries in exclusive pion electroproduction for Q(2) > 1 GeV2. I. ep -> e pi(+)n (2017). PHYSICAL REVIEW C, 95(3).
10.1103/PhysRevC.95.035206
DOI
10.1103/PhysRevC.95.035206
