dorsal/arxiv
View SchemaIs there model-independent evidence of the two-photon-exchange effect in the electron-proton elastic scattering cross section?
| Authors | Yu-Chun Chen, Chung-Wen Kao, Shin-Nan Yang |
|---|---|
| Categories | |
| ArXiv ID | nucl-th/0703017 |
| URL | https://arxiv.org/abs/nucl-th/0703017 |
| DOI | 10.1016/j.physletb.2007.07.044 |
| Journal | Phys.Lett.B652:269-274,2007 |
Abstract
We re-analyze the data of the elastic electron proton scattering to look for model-independent evidence of the two-photon-exchange (TPE) effect. In contrast to previous analyses, TPE effect is parametrized in forms which are free of kinematical-singularity, in addition to being consistent with the constraint derived from crossing symmetry and the charge conjugation. Moreover, we fix the value of $R=G_E/G_M$ as determined from the data of the polarization transfer experiment. We find that, at high $Q^2 \geq 2 GeV^2$ values, the contribution of the TPE effect to the slope of $\sigma_R$ vs. $\epsilon$ is large and comparable with that arising from $G_{E}$. It also behaves quasi-linearly in the region of current data, namely, in the range of $0.2 < \epsilon < 0.95$. Hence the fact that the current elastic $ep$ cross section data shows little nonlinearity with respect to $\epsilon$ can not be used to exclude the presence of the TPE effect. More precise data at extreme angles will be crucial for a model-independent extraction of the TPE effect.
{
"annotation_id": "6044e389-f78f-42c4-8471-0e100eaae904",
"date_created": "2026-03-02T18:00:11.601000Z",
"date_modified": "2026-03-02T18:00:11.601000Z",
"file_hash": "1b32cd38f89b7a34b57b4b81599e00af7f5d1ab0d0ce358a872c9852665b4d2f",
"private": false,
"record": {
"abstract": "We re-analyze the data of the elastic electron proton scattering to look for\nmodel-independent evidence of the two-photon-exchange (TPE) effect. In contrast\nto previous analyses, TPE effect is parametrized in forms which are free of\nkinematical-singularity, in addition to being consistent with the constraint\nderived from crossing symmetry and the charge conjugation. Moreover, we fix the\nvalue of $R=G_E/G_M$ as determined from the data of the polarization transfer\nexperiment. We find that, at high $Q^2 \\geq 2 GeV^2$ values, the contribution\nof the TPE effect to the slope of $\\sigma_R$ vs. $\\epsilon$ is large and\ncomparable with that arising from $G_{E}$. It also behaves quasi-linearly in\nthe region of current data, namely, in the range of $0.2 \u003c \\epsilon \u003c 0.95$.\nHence the fact that the current elastic $ep$ cross section data shows little\nnonlinearity with respect to $\\epsilon$ can not be used to exclude the presence\nof the TPE effect. More precise data at extreme angles will be crucial for a\nmodel-independent extraction of the TPE effect.",
"arxiv_id": "nucl-th/0703017",
"authors": [
"Yu-Chun Chen",
"Chung-Wen Kao",
"Shin-Nan Yang"
],
"categories": [
"nucl-th"
],
"doi": "10.1016/j.physletb.2007.07.044",
"journal_ref": "Phys.Lett.B652:269-274,2007",
"title": "Is there model-independent evidence of the two-photon-exchange effect in the electron-proton elastic scattering cross section?",
"url": "https://arxiv.org/abs/nucl-th/0703017"
},
"schema_id": "dorsal/arxiv",
"source": {
"execution_id": "e3a42777-c51a-4b66-8013-b20d522a9b92",
"id": "arXiv Dataset IDs",
"type": "Model",
"variant": "snapshot-2026-03-01",
"version": "0.1.0"
},
"user_id": 1000002
}