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The general spin structure of the matrix element, taking into account the two--photon exchange contribution, for the elastic electron (positron) --deuteron scattering has been derived using general symmetry properties of the hadron…

High Energy Physics - Phenomenology · Physics 2008-11-26 G. I. Gakh , E. Tomasi-Gustafsson

We examine the two-photon exchange corrections to elastic electron-proton scattering within a dispersive approach, including contributions from both Nucleon and Delta intermediate states. The dispersive analysis avoids off-shell…

Nuclear Theory · Physics 2017-06-21 P. G. Blunden , W. Melnitchouk

The parity-conserving single-spin beam asymmetry of elastic electron-proton scattering is induced by an absorptive part of the two-photon exchange amplitude. We demonstrate that this asymmetry has logarithmic and double-logarithmic…

High Energy Physics - Phenomenology · Physics 2014-11-17 Andrei Afanasev , N. P. Merenkov

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

We consider emission of a photon by an electron in the field of a strong laser wave. Polarization effects in this process are important for a number of physical problems. We discuss a probability of this process for circularly polarized…

High Energy Physics - Phenomenology · Physics 2007-05-23 D. Yu. Ivanov , G. L. Kotkin , V. G. Serbo

We review the experimental and theoretical status of elastic electron scattering and elastic low-energy photon scattering (with both real and virtual photons) from the nucleon. As a consequence of new experimental facilities and new…

Nuclear Experiment · Physics 2008-11-26 Charles Earl Hyde-Wright , Kees de Jager

A detailed study of two-photon exchange in unpolarized and polarized elastic electron--nucleon scattering is presented, taking particular account of nucleon finite size effects. Contributions from nucleon elastic intermediate states are…

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

We present a theoretical approach to investigate the scattering of polarized electrons from light nuclei using the multipole expansion for the scattering cross section within the framework of the unified electroweak theory. Scattering…

Nuclear Theory · Physics 2026-05-01 Minh Truong Vo , Vu Dong Tran , Quang Hung Nguyen

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

Coincidence reactions of the type $\svec{A}(\svec{e},e'N)B$ involving the scattering of polarized electrons from deformed polarized targets are discussed within the context of the plane--wave impulse approximation. A general expression for…

High Energy Physics - Phenomenology · Physics 2009-10-22 J. A. Caballero , T. W. Donnelly , G. I. Poulis , E. Garrido , E. Moya de Guerra

Structure functions and polarization observables in elastic scattering of longitudinally polarized electron on polarized deuteron are considered within approximation of one-photon + two-photon exchange. It is shown that contribution of…

After recalling the arguments for possible excess of two-photon contribution over $\alpha$-counting, model independent statements about the consequences on the observables will be given. The relevant experimental data are discussed:…

High Energy Physics - Phenomenology · Physics 2018-07-04 Egle Tomasi-Gustafsson , Simone Pacetti

We review recent developments in the theoretical investigation of the nucleon polarizabilities. We first report on the static polarizabilities as measured in real Compton scattering, comparing and interpreting the results from various…

High Energy Physics - Phenomenology · Physics 2012-01-17 B. Pasquini , D. Drechsel , M. Vanderhaeghen

We estimate the two-photon exchange contribution to elastic electron-proton scattering at large momentum transfer through the scattering off a parton in the proton. We relate the process on the nucleon to the generalized parton…

High Energy Physics - Phenomenology · Physics 2009-09-11 Y. C. Chen , A. Afanasev , S. J. Brodsky , C. E. Carlson , M. Vanderhaeghen

The problem of electron-proton scattering is handed over both the elastic and inelastic scattering. Two models are presented in this sense. The first, depends on the multi photon exchange ladder diagram, where the transition matrix is…

High Energy Physics - Phenomenology · Physics 2007-05-23 M. T. Hussein , R. Elmualed , N. M. Hassan

It is found that the differential cross section of photon-photon scattering is a function of the degree of polarization entanglement of the two-photon state. A reduced, general expression for the differential cross section of photon-photon…

Quantum Physics · Physics 2017-01-11 Dennis Rätzel , Martin Wilkens , Ralf Menzel

Below pion threshold virtual Compton scattering off the nucleon gives access to the generalized electromagnetic polarizabilities. Different theoretical results for the generalized polarizabilities have been compared. In particular, the…

High Energy Physics - Phenomenology · Physics 2007-05-23 A. Metz , B. Pasquini , D. Drechsel

A theoretical description of nucleon knockout reactions initiated by polarized electron scattering from polarized nuclei is presented. Explicit expressions for the complete set of reduced response functions (independent of the polarization…

Nuclear Theory · Physics 2008-11-26 J. E. Amaro , T. W. Donnelly

We argue that, in many situations, fits to elastic scattering data that were historically, and frequently still are, considered `good', are not justifiably so describable. Information about the dynamics of nucleon-nucleus and…

Nuclear Theory · Physics 2017-04-12 R. S. Mackintosh

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…

High Energy Physics - Phenomenology · Physics 2008-12-03 A. P. Kobushkin , D. L. Borisyuk