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Current status of the two-boson exchange contributions to elastic electron-proton scattering, both for parity conserving and parity-violating, is briefly reviewed. How the discrepancy in the extraction of elastic nucleon form factors…

Nuclear Theory · Physics 2015-05-30 Shin Nan Yang

The proton elastic form factor ratio shows a discrepancy between measurements using the Rosenbluth technique in unpolarized beam and target experiments and measurements using polarization degrees of freedom. The proposed explanation of this…

Nuclear Experiment · Physics 2021-05-12 Jan C. Bernauer , Volker D. Burkert , Ethan Cline , Axel Schmidt , Youri Sharabian

We calculate two-photon exchange (TPE) amplitudes for the elastic electron-proton scattering, and take into account intermediate hadronic states containing \pi N system with total angular momentum 1/2 or 3/2, which includes 8 different…

High Energy Physics - Phenomenology · Physics 2015-09-16 Dmitry Borisyuk , Alexander Kobushkin

We estimate the two-photon exchange contribution to elastic electron-proton scattering at large momentum transfer by using a quark-parton representation of virtual Compton scattering. We thus can relate the two-photon exchange amplitude to…

High Energy Physics - Phenomenology · Physics 2008-11-26 Andrei V. Afanasev , Stanley J. Brodsky , Carl E. Carlson , Yu-Chun Chen , Marc Vanderhaeghen

Higher-order QED effects play an important role in precision measurements of nucleon elastic form factors in electron scattering. Here we introduce a two-photon exchange QED correction to the parity-violating polarization asymmetry of…

High Energy Physics - Phenomenology · Physics 2008-11-26 Andrei V. Afanasev , Carl E. Carlson

We present an improved evaluation of the two-photon exchange correction to the unpolarized lepton-proton elastic scattering process at very low-energies relevant to the MUSE experiment, where only the dominant intermediate elastic proton is…

High Energy Physics - Phenomenology · Physics 2025-04-02 Rakshanda Goswami , Pulak Talukdar , Bhoomika Das , Udit Raha , Fred Myhrer

Leading electroweak corrections play an important role in precision measurements of the strange form factors. We calculate the two-photon-exchange (TPE) and $\gamma Z$-exchange corrections to the parity-violating asymmetry of the elastic…

High Energy Physics - Phenomenology · Physics 2008-11-26 Hai Qing Zhou , Chung Wen Kao , Shin Nan Yang

Measurements of the proton's form factor ratio made with polarization transfer show a striking discrepancy relative to the ratio extracted from unpolarized elastic electron-proton scattering cross sections. One hypothesis is that the…

Nuclear Experiment · Physics 2021-11-16 Axel Schmidt

We investigate the two-photon corrections to the process $p\bar{p} \to e^+e^-$ at large momentum transfer, aimed to access the time-like nucleon form factors. We estimate the two-photon corrections using a hard rescattering mechanism, which…

High Energy Physics - Phenomenology · Physics 2015-03-18 Julia Guttmann , Nikolai Kivel , Marc Vanderhaeghen

The presence of two photon exchange in $ep$ elastic scattering and in the crossed processes ($\bar p +p\leftrightarrow \ell^+ +\ell^-$, $\ell=e$ or $\mu$) is discussed in terms of three complex amplitudes which are functions of two…

Nuclear Theory · Physics 2007-05-23 E. Tomasi-Gustafsson

The radiative corrections to elastic electron-proton scattering are analyzed in a hadronic model including the finite size of the nucleon. For initial electron energies above 8 GeV and large scattering angles, the proton vertex correction…

Nuclear Theory · Physics 2009-11-06 L. C. Maximon , J. A. Tjon

We consider radiative corrections to polarization observables in elastic electron-proton scattering, in particular, for the polarization transfer measurements of the proton form factor ratio $\mu G_E/G_M$. The corrections are of two types:…

High Energy Physics - Phenomenology · Physics 2014-08-27 Dmitry Borisyuk , Alexander Kobushkin

We present an exact evaluation of the two-photon exchange contribution to the elastic lepton-proton scattering process at low-energies using heavy baryon chiral perturbation theory. The evaluation is performed including next-to-leading…

High Energy Physics - Phenomenology · Physics 2023-11-30 Poonam Choudhary , Udit Raha , Fred Myhrer , Dipankar Chakrabarti

The effects of multi-photon-exchange and other higher-order QED corrections on elastic electron-proton scattering have been a subject of high experimental and theoretical interest since the polarization transfer measurements of the proton…

Nuclear Experiment · Physics 2021-06-23 A. J. R. Puckett , J. C. Bernauer , A. Schmidt

Recent theoretical developments in the studies of two-photon exchange effects in elastic electron-proton scattering are reviewed. Two-photon exchange mechanism is considered a likely source of discrepancy between polarized and unpolarized…

High Energy Physics - Phenomenology · Physics 2017-08-23 Andrei V. Afanasev

Employing the systematic framework of soft-collinear effective theory (SCET) we perform an improved calculation of the leading-power contributions to the double radiative $B_{d, \, s}$-meson decay amplitudes in the heavy quark expansion. We…

High Energy Physics - Phenomenology · Physics 2021-02-03 Yue-Long Shen , Yu-Ming Wang , Yan-Bing Wei

It is demonstrated that two-photon exchange (TPE) corrections to the cross-section of unpolarized semi-inclusive deep-inelastic scattering (SIDIS) generate azimuthal-dependent terms and the corresponding $\braket{{\cos{(n\phi)}}}$ moments.…

High Energy Physics - Phenomenology · Physics 2025-04-25 Stinson Lee , Andrei Afanasev

We propose possible methods to measure the nucleon electromagnetic form factors in presence of two-photon exchange. Using a general parametrization of the spin structure of the matrix element for elastic $eN$-scattering, in terms of three…

Nuclear Theory · Physics 2009-11-10 M. P. Rekalo , E. Tomasi-Gustafsson

We compute the two photon exchange contributions to elastic scattering of polarized electrons from target protons. We use a nonlocal field theory formalism for this calculation. The formalism maintains gauge invariance and provides a…

High Energy Physics - Phenomenology · Physics 2008-12-18 Pankaj Jain , Satish D. Joglekar , Subhadip Mitra

We calculate the effects on the elastic electron-proton scattering cross section of the two-photon exchange contribution with an intermediate $\Delta$ resonance. The $\Delta$ two-photon exchange contribution is found to be smaller in…

Nuclear Theory · Physics 2014-11-18 S. Kondratyuk , P. G. Blunden , W. Melnitchouk , J. A. Tjon