Abstract
Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive π0 electroproduction reaction γ∗p → pπ0, expanding an analysis of the γ∗p → 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.
Document Type
Article
Publication Date
3-20-2017
Digital Object Identifier (DOI)
https://doi.org/10.1103/PhysRevC.95.035207
Repository Citation
Bosted, P. E.; Kim, A.; Adhikari, K. P.; Adikaram, D.; Akbar, Z.; Amaryan, M. J.; Anefalos Pereira, S.; Avakian, H.; Badui, R. A.; Ball, J.; Balossino, I.; Battaglieri, M.; Bedlinskiy, I.; Biselli, A. S.; Boiarinov, S.; Briscoe, W. J.; Brooks, W. K.; Bültmann, S.; Burkert, V. D.; Cao, T.; Carman, D. S.; Celentano, A.; Chandavar, S.; Charles, G.; Chetry, T.; Ciullo, G.; Clark, L.; Colaneri, L.; Cole, P. L.; Contalbrigo, M.; and Gohn, Wesley P., "Target and Beam-Target Spin Asymmetries in Exclusive Pion Electroproduction for Q2 > 1 GeV2. II. ep → eπ0p" (2017). Physics and Astronomy Faculty Publications. 512.
https://uknowledge.uky.edu/physastron_facpub/512
Supplemental Material
Notes/Citation Information
Published in Physical Review C, v. 95, issue 3, 035207, p. 1-12.
©2017 American Physical Society
The copyright holder has granted permission for posting the article here.
Due to the large number of authors, only the first 30 and the authors affiliated with the University of Kentucky are listed in the author section above. For the complete list of authors, please download this article or visit: https://doi.org/10.1103/PhysRevC.95.035207
This group of authors is collectively known as the CLAS Collaboration.