Study of Two-Photon Exchange via the Beam Transverse Single Spin Asymmetry in Electron-Proton Elastic Scattering at Forward Angles over a Wide Energy Range.
Journal
Physical review letters
ISSN: 1079-7114
Titre abrégé: Phys Rev Lett
Pays: United States
ID NLM: 0401141
Informations de publication
Date de publication:
27 Mar 2020
27 Mar 2020
Historique:
revised:
28
02
2020
received:
14
02
2020
accepted:
28
02
2020
entrez:
14
4
2020
pubmed:
14
4
2020
medline:
14
4
2020
Statut:
ppublish
Résumé
We report on a new measurement of the beam transverse single spin asymmetry in electron-proton elastic scattering, A_{⊥}^{ep}, at five beam energies from 315.1 to 1508.4 MeV and at a scattering angle of 30°<θ<40°. The covered Q^{2} values are 0.032, 0.057, 0.082, 0.218, 0.613 (GeV/c)^{2}. The measurement clearly indicates significant inelastic contributions to the two-photon-exchange (TPE) amplitude in the low-Q^{2} kinematic region. No theoretical calculation is able to reproduce our result. Comparison with a calculation based on unitarity, which only takes into account elastic and πN inelastic intermediate states, suggests that there are other inelastic intermediate states such as ππN, KΛ, and ηN. Covering a wide energy range, our new high-precision data provide a benchmark to study those intermediate states.
Identifiants
pubmed: 32281834
doi: 10.1103/PhysRevLett.124.122003
doi:
Types de publication
Journal Article
Langues
eng
Sous-ensembles de citation
IM