Polarization Transfer in Wide-Angle Compton Scattering and Single-Pion Photoproduction from the Proton
Name
PhysRevLett.115.152001.pdf
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543.41 KB
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Checksum (MD5)
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Author(s)
Fanelli, C.
Cisbani, E.
Hamilton, D. J.
Salmé, G.
Wojtsekhowski, B.
Ahmidouch, A.
Annand, J. R. M.
Baghdasaryan, H.
Beaufait, J.
Bosted, P.
Date Issued
October 2015
Journal
Physical Review Letters
Publisher
American Physical Society
Citation
Fanelli, C., et al. "Polarization Transfer in Wide-Angle Compton Scattering and Single-Pion Photoproduction from the Proton." Phys. Rev. Lett. 115, 152001 (October 2015). © 2015 American Physical Society
Version
Final published version
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 θ[p over cm] = 70°. The longitudinal transfer K[subscript LL], 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.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1103/PhysRevLett.115.152001
