Is there model-independent evidence of the two-photon-exchange effect in the electron-proton elastic scattering cross section?

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dc.creatorChen, Yu-Chun
dc.creatorKao, Chung-Wen
dc.creatorYang, Shin-Nan
dc.date2007-03-07
dc.date2007-08-28
dc.date.accessioned2026-07-07T12:00:18Z
dc.date.available2026-07-07T12:00:18Z
dc.descriptionWe 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 $σ_R$ vs. $ε$ 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 $0.2 < ε< 0.95$. Hence the fact that the current elastic $ep$ cross section data shows little nonlinearity with respect to $ε$ 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.
dc.description11 pages, 4 figures
dc.identifierhttps://arxiv.org/abs/nucl-th/0703017
dc.identifierhttp://arxiv.org/abs/nucl-th/0703017
dc.identifierPhys.Lett.B652:269-274,2007
dc.identifierdoi:10.1016/j.physletb.2007.07.044
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/206819
dc.subjectNuclear Theory
dc.titleIs there model-independent evidence of the two-photon-exchange effect in the electron-proton elastic scattering cross section?
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