Document Type
Article
Department/Program
Physics
Journal Title
Physical Review Letters
Pub Date
2015
Volume
115
Issue
15
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 theta(p)(cm) cm = 70 degrees. The longitudinal transfer K-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 similar to 3 times larger than predicted by the generalized-parton-distribution-based calculations, which indicates a significant unknown contribution to the scattering amplitude.
Recommended Citation
Fanelli, C.; Salme, G.; Cisbani, E.; Kelleher, A.; Meziane, M.; Pentchev, L.; and Perdrisat, C. F., Polarization Transfer in Wide-Angle Compton Scattering and Single-Pion Photoproduction from the Proton (2015). Physical Review Letters, 115(15).
10.1103/PhysRevLett.115.152001
DOI
10.1103/PhysRevLett.115.152001
