Related papers: Two-Photon Exchange and Electromagnetic Proton For…
We estimate two-photon exchange contribution to the process $e^+ +e^- \to p + \bar{p}$. The two-photon exchange corrections to double spin polarization observables and form factors in the time-like region are calculated. The corrections are…
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…
The cross section of elastic electron-proton scattering taking place in an electron gas is calculated within the Closed Time Path method. It is found to be the sum of two terms, one being the expression in the vacuum except that it involves…
We present a study of the two-photon-exchange ($2\gamma$-exchange) corrections to the $S$-levels in muonic ($\mu$D) and ordinary (D) deuterium within the pionless effective field theory (pionless EFT). Our calculation proceeds up to…
Significant discrepancies have been observed between proton form factors as measured by Rosenbluth separation and polarization transfer techniques. There are indications that this difference may be caused by corrections to the one photon…
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…
Measurements of the ratio of the proton elastic form factors ($\mu_pG_E/G_M$) using Rosenbluth separation and those using polarization-based techniques show a strong discrepancy, which increases as a function of $Q^2$. The contribution of…
Intensive theoretical and experimental efforts over the past decade have aimed at explaining the discrepancy between data for the proton electric to magnetic form factor ratio, $G_{E}/G_{M}$, obtained separately from cross section and…
We discuss the target and beam normal spin asymmetries in elastic electron-nucleon scattering which depend on the imaginary part of two-photon exchange processes between electron and nucleon. In particular, we estimate these transverse spin…
We calculated two--photon exchange effects for elastic electron--proton scattering at high momentum transfers. The corresponding nucleon Compton amplitude is defined by two space--like virtual photons that appear to have significant…
We report the first measurement of the vector analyzing power in inclusive transversely polarized elastic electron-proton scattering at Q^2 = 0.1 (GeV/c)^2 and large scattering angles. This quantity should vanish in the single virtual…
We apply a subtracted dispersion relation (DR) formalism with the aim to improve predictions for the two-photon exchange (TPE) corrections to elastic electron-proton scattering observables at small momentum transfers. We study the formalism…
The elastic backward proton-deuteron scattering is analyzed within a covariant approach based on the Bethe-Salpeter equation with realistic meson-exchange interaction. Contributions of the one-nucleon and one-pion exchange mechanisms to the…
We perform detailed calculations of two-photon-exchange QED corrections to the cross section of pion electroproduction. The results are obtained with and without the soft-photon approximation; analytic expressions for the radiative…
The OLYMPUS collaboration reports on a precision measurement of the positron-proton to electron-proton elastic cross section ratio, $R_{2\gamma}$, a direct measure of the contribution of hard two-photon exchange to the elastic cross…
The charge and magnetic form factors of light nuclei, mainly for mass numbers A<=4, provide a sensitive test of our understanding of nuclei. A number of "exact" calculations of the wave functions starting from the nucleon-nucleon…
Recent measurements of recoil polarization in elastic scattering have been used to extract the ratio of the electric to the magnetic proton form factors. These results disagree with Rosenbluth extractions from cross section measurements,…
Elastic and inelastic cross section of proton-proton and electron-proton scattering are discussed. Special attention is given to elastic scattering and to the striking difference between the data of these two kinds of experiments. It is…
The beam-normal single-spin asymmetry, $B_n$, exists in the scattering of high energy electrons, polarized transverse to their direction of motion, from nuclear targets. To first order, this asymmetry is caused by the interference of the…
We investigate the effect of high order radiative corrections in unpolarized electron proton elastic scattering and compare with the calculations at lowest order, which are usually applied to experimental data. Particular attention is…