1. Polarization Transfer in Wide-Angle Compton Scattering and Single-Pion Photoproduction from the Proton.
- Author
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Kohl, M., Li, Y., Ye, Z., Salmé, G., Fanelli, C., Kumbartzki, G., Kelleher, A., Meziane, M., Pentchev, L., Perdrisat, C. F., Khandaker, M., Lovelace, H., Punjabi, V., Wesselmann, F. R., Luo, W., Margaziotis, D. J., Markowitz, P., Mbianda, G., Miller, J., and Mkrtchyan, A.
- Subjects
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COMPTON scattering , *PION production , *PROTONS , *PARTONS , *POLARIZED beams (Nuclear physics) , *QUANTUM chromodynamics - Abstract
Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The wide-angle Compton scattering polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θcmp=70°. The longitudinal transfer KLL, measured to be 0.645±0.059±0.048, where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton. However, the observed value is ~3 times larger than predicted by the generalized-parton-distribution-based calculations, which indicates a significant unknown contribution to the scattering amplitude. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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