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
| Autor: | J. Van de Wiele, M. Zambrana, S. Baunack, U. Müller, E. Schilling, F. E. Maas, M. Morlet, Y. Imai, Wouter Deconinck, C. Weinrich, R. Frascaria, Mikhail Gorchtein, J. Diefenbach, B. Gou, Harald Merkel, M. C. Mora Espí, I. Zimmermann, D. von Harrach, B. Gläser, S. Ong, R. Kunne, S. Kowalski, K. Aulenbacher, Dominik Becker, J. Arvieux, R. Kothe, E. M. Kabuß, L. Capozza, D. Balaguer Ríos |
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| Přispěvatelé: | Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11) |
| Rok vydání: | 2020 |
| Předmět: |
Proton
media_common.quotation_subject FOS: Physical sciences General Physics and Astronomy Electron [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex] 01 natural sciences Asymmetry beam: energy electron p: elastic scattering pi nucleon: intermediate state benchmark 0103 physical sciences eta nucleon polarization: transverse unitarity Nuclear Experiment (nucl-ex) 010306 general physics Nuclear Experiment media_common Spin-½ Physics Elastic scattering exchange: two-photon Unitarity Scattering scattering 3. Good health transverse intermediate state Automatic Keywords kinematics Elementary Particles and Fields High Energy Physics::Experiment Atomic physics spin: asymmetry Beam (structure) experimental results |
| Zdroj: | Physical Review Letters Physical Review Letters, American Physical Society, 2020, 124 (12), pp.122003. ⟨10.1103/PhysRevLett.124.122003⟩ |
| ISSN: | 1079-7114 0031-9007 |
| DOI: | 10.1103/physrevlett.124.122003 |
| Popis: | We report on a new measurement of the beam transverse single spin asymmetry in electron-proton elastic scattering, $A^{ep}_{\perp}$, at five beam energies from 315.1 MeV to 1508.4 MeV and at a scattering angle of $30^{\circ} < \theta < 40^{\circ}$. 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 $\mathrm{\pi N}$ inelastic intermediate states, suggests that there are other inelastic intermediate states such as $\mathrm{\pi \pi N}$, $\mathrm{K \Lambda}$ and $\mathrm{\eta N}$. Covering a wide energy range, our new high-precision data provide a benchmark to study those intermediate states. Comment: 6 pages, 3 figures |
| Databáze: | OpenAIRE |
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