dorsal/arxiv
View SchemaTwo-photon exchange in elastic electron-nucleon scattering
| Authors | P. G. Blunden, W. Melnitchouk, J. A. Tjon |
|---|---|
| Categories | |
| ArXiv ID | nucl-th/0506039 |
| URL | https://arxiv.org/abs/nucl-th/0506039 |
| DOI | 10.1103/PhysRevC.72.034612 |
| Journal | Phys.Rev.C72:034612,2005 |
Abstract
A detailed study of two-photon exchange in unpolarized and polarized elastic electron--nucleon scattering is presented, taking particular account of nucleon finite size effects. Contributions from nucleon elastic intermediate states are found to have a strong angular dependence, which leads to a partial resolution of the discrepancy between the Rosenbluth and polarization transfer measurements of the proton electric to magnetic form factor ratio, G_E/G_M. The two-photon exchange contribution to the longitudinal polarization transfer P_L is small, whereas the contribution to the transverse polarization transfer P_T is enhanced at backward angles by several percent, increasing with Q^2. This gives rise to a small, ~3% suppression of G_E/G_M obtained from the polarization transfer ratio P_T/P_L at large Q^2. We also compare the two-photon exchange effects with data on the ratio of e^+ p to e^- p cross sections, which is predicted to be enhanced at backward angles. Finally, we evaluate the corrections to the form factors of the neutron, and estimate the elastic intermediate state contribution to the ^3He form factors.
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"abstract": "A detailed study of two-photon exchange in unpolarized and polarized elastic\nelectron--nucleon scattering is presented, taking particular account of nucleon\nfinite size effects. Contributions from nucleon elastic intermediate states are\nfound to have a strong angular dependence, which leads to a partial resolution\nof the discrepancy between the Rosenbluth and polarization transfer\nmeasurements of the proton electric to magnetic form factor ratio, G_E/G_M. The\ntwo-photon exchange contribution to the longitudinal polarization transfer P_L\nis small, whereas the contribution to the transverse polarization transfer P_T\nis enhanced at backward angles by several percent, increasing with Q^2. This\ngives rise to a small, ~3% suppression of G_E/G_M obtained from the\npolarization transfer ratio P_T/P_L at large Q^2. We also compare the\ntwo-photon exchange effects with data on the ratio of e^+ p to e^- p cross\nsections, which is predicted to be enhanced at backward angles. Finally, we\nevaluate the corrections to the form factors of the neutron, and estimate the\nelastic intermediate state contribution to the ^3He form factors.",
"arxiv_id": "nucl-th/0506039",
"authors": [
"P. G. Blunden",
"W. Melnitchouk",
"J. A. Tjon"
],
"categories": [
"nucl-th"
],
"doi": "10.1103/PhysRevC.72.034612",
"journal_ref": "Phys.Rev.C72:034612,2005",
"title": "Two-photon exchange in elastic electron-nucleon scattering",
"url": "https://arxiv.org/abs/nucl-th/0506039"
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