Related papers: Proton radii and two-photon exchange
We review recent theoretical and experimental progress on the role of two-photon exchange (TPE) in electron-proton scattering at low to moderate momentum transfers. We make a detailed comparison and analysis of the results of competing…
We discuss effects of two-photon exchange (TPE) in various observables of the elastic ep-scattering. The imaginary part of the TPE amplitude manifests in target and beam normal spin asymmetries. The real part contributes to the…
The current status of the determination of corrections to the hyperfine splitting of the ground state in hydrogen is considered. Improved calculations are provided taking into account the most recent value for the proton charge radius.…
The proton elastic form factor ratio can be measured either via Rosenbluth separation in an unpolarized beam and target experiment, or via the use of polarization degrees of freedom. However, data produced by these two approaches show a…
The proton radius has been measured in electron-proton scattering experiments and laser based spectroscopy of muonic hydrogen. The latter method is based on the precise calculations for the atomic energy levels in the approximation of…
The effects of two-photon exchange corrections, suggested to explain the difference between measurements of the proton elastic electromagnetic form factors using the polarization transfer and Rosenbluth techniques, have been studied in…
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…
We extend the general formalism of two-photon exchange to elastic lepton-nucleon scattering by accounting for all lepton mass terms. We then perform a numerical estimate of the muon-proton scattering at low momentum transfer in view of the…
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…
It is shown that the amplitude of elastic ed scattering beyond Born approximation contains six generalized form factors, but only three linearly independent combinations of them (generalized charge, quadrupole and magnetic form factors)…
The elastic electron-proton scattering data are analysed in order to determine proton charge and magnetic rms radii, r_E and r_M. Along with the usual statistical error, we try to estimate a systematic error in the radii, caused by the…
We revisit the question of the contributions of two-photon exchange with $\Delta(1232)$ excitation to the electron-proton scattering in a hadronic model. Three improvements over the previous calculations are made, namely, correct vertex…
The general form of the cross section as well as the polarizations of electron-deuteron elastic scattering are given. Two-photon exchange effects are analyzed. Possible signatures of the two-photon exchange effects in the electron-deuteron…
The presence of $2\gamma$-exchange in electron proton elastic scattering is discussed. From C-invariance and crossing symmetry, $2\gamma$ contribution induces a specific dependence of the reduced cross section on the variable $\epsilon$. No…
We calculate contributions of hadron resonances to two-photon exchange effects in electron-proton scattering. In addition to the nucleon and P33 resonance, the following heavier resonances are included as intermediate states in the…
We reanalyze electron-proton scattering data in the momentum transfer region $Q^2 < 1\ GeV^2$, which were used to determine proton electric radius, with main focus on the Mainz experiment (Bernauer et al., 2010). We examine dependence of…
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…
Multi-photon exchange contributions are important in extracting the proton charge radius from elastic electron--proton scattering. So far, only diagrams associated with the exchange of a second photon have been evaluated. At the very low…
A detailed examination of issues associated with proton radius extractions from elastic electron-proton scattering experiments is presented. Sources of systematic uncertainty and model dependence in the extractions are discussed, with an…
We address the discrepancy between the Rosenbluth and polarization transfer data for the electromagnetic form factors of the nucleon. Assuming that the effect of two-photon corrections on the polarization transfer data is negligible, we…