Document Type
Article
Department/Program
Physics
Journal Title
Physical Review Letters
Pub Date
9-2020
Publisher
American Physical Society
Volume
125
Issue
11
Abstract
A beam-normal single-spin asymmetry generated in the scattering of transversely polarized electrons from unpolarized nucleons is an observable related to the imaginary part of the two-photon exchange process. We report a 2% precision measurement of the beam-normal single-spin asymmetry in elastic electron-proton scattering with a mean scattering angle of theta_lab = 7.9 degrees and a mean energy of 1.149 GeV. The asymmetry result is B_n = -5.194 +- 0.067 (stat) +- 0.082 (syst) ppm. This is the most precise measurement of this quantity available to date and therefore provides a stringent test of two-photon exchange models at far-forward scattering angles (theta_lab -> 0) where they should be most reliable.
Recommended Citation
Androic, D.; Armstrong, David S.; and et al., Precision Measurement of the Beam-Normal Single-Spin Asymmetry in Forward-Angle Elastic Electron-Proton Scattering (2020). Physical Review Letters, 125(11).
https://doi.org/10.1103/PhysRevLett.125.112502
DOI
https://doi.org/10.1103/PhysRevLett.125.112502
Publisher Statement
This work is made available for educational and personal use only. Copyright is credited to the authors. Any other uses should be directed to the publisher.
