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E. Tomasi-gustafsson - One of the best experts on this subject based on the ideXlab platform.
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Two-photon exchange: myth and history
2017Co-Authors: E. Tomasi-gustafsson, Simone PacettiAbstract: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: (polarized and Unpolarized) Electron and positron elastic scattering on the proton, as well as annihilation data. A reanalysis of Unpolarized Electron–proton elastic scattering data is presented in terms of the electric to magnetic form factor squared ratio. This observable is in principle more robust against experimental correlations and global normalizations. The present analysis shows indeed that it is a useful quantity that contains reliable and coherent information. The comparison with the ratio extracted from the measurement of the longitudinal to transverse polarization of the recoil proton in polarized Electron–proton scattering shows that the results are compatible. These results bring a decisive piece of information in the controversy on the deviation of the proton form factors from the dipole dependence.
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Radiative corrections for Electron-proton elastic scattering taking into account high orders and hard-photon emission
Physical Review C, 2014Co-Authors: E. A. Kuraev, Yu. M. Bystritskiy, A. I. Ahmadov, E. Tomasi-gustafssonAbstract: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 devoted to the $\epsilon$ dependence of radiative corrections, which is directly related to the electric proton form factor. We consider in particular the effects of the interference terms for soft and hard photon emission. Both quadratic amplitude describing the collinear emission along the scattered Electron as well as the interference with the amplitudes of emission from the initial Electron and the emission from protons are important in leading and next to leading approximation and they may compensate in particular kinematical conditions.
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High order radiative corrections for Unpolarized Electron proton elastic scattering at low $Q^2$
arXiv: High Energy Physics - Phenomenology, 2008Co-Authors: E. A. Kuraev, Yu. M. Bystritskiy, S. Bakmaev, V. V. Bytev, E. Tomasi-gustafssonAbstract: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. We show that higher order terms play a role, starting from values of the momentum transfer squared, $Q^2$, larger than the Electron mass. Particular attention is devoted to the $\epsilon$ dependence of radiative corrections.
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On radiative corrections for Unpolarized Electron-proton elastic scattering
Physics of Particles and Nuclei Letters, 2007Co-Authors: E. Tomasi-gustafssonAbstract:A statistical analysis of the elastic Unpolarized Electron-proton scattering data shows that at large momentum transfer the size and the ε dependence of the radiative corrections, as traditionally calculated and applied, may induce large correlations of the parameters of the Rosenbluth fit, which prevent a correct extraction of the electric proton form factor. Using the Electron QED structure (radiation) function approach, the cross section of elastic Electron-proton scattering in leading and next-to-leading approximations is calculated and expressed as a correction to the Born cross section, which is different for the electric and magnetic contributions. When properly applied to the data, it may yield the solution to the problem of the discrepancy of the polarized and Unpolarized results on Electron-proton scattering.
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Structure function method applied to polarized and Unpolarized Electron-proton scattering: A solution of the G E ( p ) / G M ( p ) discrepancy
Physical Review C, 2007Co-Authors: Yu. M. Bystritskiy, E. A. Kuraev, E. Tomasi-gustafssonAbstract:The cross section for polarized and Unpolarized Electron-proton scattering is calculated by taking into account radiative corrections in leading and next-to-leading logarithmic approximation. The expression of the cross section is formally similar to the cross section of the Drell-Yan process, where the structure functions of the Electron play the role of Drell-Yan probability distributions. The interference of the Born amplitude with the two-photon exchange amplitude (box-type diagrams) is expressed as a contribution to the K factor. It is calculated under the assumption that proton form factors decrease rapidly with the momentum transfer squared and that the momentum is equally shared between the two photons. The calculation of the box amplitude is done when the intermediate state is the proton or the {delta} resonance. The results of numerical estimations show that the present calculation of radiative corrections can bring into agreement the conflicting experimental results on proton electromagnetic form factors and that the two-photon contribution is very small.
Yu. M. Bystritskiy - One of the best experts on this subject based on the ideXlab platform.
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Radiative corrections for Electron-proton elastic scattering taking into account high orders and hard-photon emission
Physical Review C, 2014Co-Authors: E. A. Kuraev, Yu. M. Bystritskiy, A. I. Ahmadov, E. Tomasi-gustafssonAbstract: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 devoted to the $\epsilon$ dependence of radiative corrections, which is directly related to the electric proton form factor. We consider in particular the effects of the interference terms for soft and hard photon emission. Both quadratic amplitude describing the collinear emission along the scattered Electron as well as the interference with the amplitudes of emission from the initial Electron and the emission from protons are important in leading and next to leading approximation and they may compensate in particular kinematical conditions.
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Possible method for measuring the proton form factors in processes with and without proton spin flip
JETP Letters, 2008Co-Authors: M. V. Galynskii, E. A. Kuraev, Yu. M. BystritskiyAbstract:The ratio of the squares of the electric and magnetic proton form factors is shown to be proportional to the ratio of the cross sections for the elastic scattering of an Unpolarized Electron on a partially polarized proton with and without proton spin flip. The initial proton at rest should be polarized along the direction of the motion of the final proton. Similar results are valid for both radiative ep scattering and the photoproduction of pairs on a proton in the Bethe-Heitler kinematics. When the initial proton is fully polarized in the direction of the motion of the final proton, the cross section for the ep → ep process, as well as for the ep → epγ and γp → $$ e\bar ep $$ processes, without (with) proton spin flip is expressed only in terms of the square of the electric (magnetic) proton form factor. Such an experiment on the measurement of the cross sections without and with proton spin flip would make it possible to acquire new independent data on the behavior of G _ E ^2 ( Q ^2) and G _ M ^2 ( Q ^2), which are necessary for resolving the contradictions appearing after the experiment of the JLab collaboration on the measurement of the proton form factors with the method of polarization transfer from the initial Electron to the final proton.
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High order radiative corrections for Unpolarized Electron proton elastic scattering at low $Q^2$
arXiv: High Energy Physics - Phenomenology, 2008Co-Authors: E. A. Kuraev, Yu. M. Bystritskiy, S. Bakmaev, V. V. Bytev, E. Tomasi-gustafssonAbstract: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. We show that higher order terms play a role, starting from values of the momentum transfer squared, $Q^2$, larger than the Electron mass. Particular attention is devoted to the $\epsilon$ dependence of radiative corrections.
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high order radiative corrections for Unpolarized Electron proton elastic scattering at low q 2
arXiv: High Energy Physics - Phenomenology, 2008Co-Authors: E. A. Kuraev, Yu. M. Bystritskiy, S. Bakmaev, V. V. Bytev, Egle TomasigustafssonAbstract: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. We show that higher order terms play a role, starting from values of the momentum transfer squared, $Q^2$, larger than the Electron mass. Particular attention is devoted to the $\epsilon$ dependence of radiative corrections.
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Structure function method applied to polarized and Unpolarized Electron-proton scattering: A solution of the G E ( p ) / G M ( p ) discrepancy
Physical Review C, 2007Co-Authors: Yu. M. Bystritskiy, E. A. Kuraev, E. Tomasi-gustafssonAbstract:The cross section for polarized and Unpolarized Electron-proton scattering is calculated by taking into account radiative corrections in leading and next-to-leading logarithmic approximation. The expression of the cross section is formally similar to the cross section of the Drell-Yan process, where the structure functions of the Electron play the role of Drell-Yan probability distributions. The interference of the Born amplitude with the two-photon exchange amplitude (box-type diagrams) is expressed as a contribution to the K factor. It is calculated under the assumption that proton form factors decrease rapidly with the momentum transfer squared and that the momentum is equally shared between the two photons. The calculation of the box amplitude is done when the intermediate state is the proton or the {delta} resonance. The results of numerical estimations show that the present calculation of radiative corrections can bring into agreement the conflicting experimental results on proton electromagnetic form factors and that the two-photon contribution is very small.
Egle Tomasigustafsson - One of the best experts on this subject based on the ideXlab platform.
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form factor ratio from Unpolarized elastic Electron proton scattering
Physical Review C, 2016Co-Authors: Simone Pacetti, Egle TomasigustafssonAbstract:A reanalysis of Unpolarized Electron-proton elastic scattering data is done in terms of the electric to magnetic form factor squared ratio. This observable is in principle more robust against experimental correlations and global normalizations. The present analysis shows indeed that it is a useful quantity that contains reliable and coherent information. The comparison with the ratio extracted from the measurement of the longitudinal to transverse polarization of the recoil proton in polarized Electron-proton scattering shows that the results are compatible within the experimental errors. Limits are set on the kinematics where the physical information on the form factors can be safely extracted. The results presented in this work bring a decisive piece of information to the controversy on the deviation of the proton form factors from the dipole dependence.
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high order radiative corrections for Unpolarized Electron proton elastic scattering at low q 2
arXiv: High Energy Physics - Phenomenology, 2008Co-Authors: E. A. Kuraev, Yu. M. Bystritskiy, S. Bakmaev, V. V. Bytev, Egle TomasigustafssonAbstract: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. We show that higher order terms play a role, starting from values of the momentum transfer squared, $Q^2$, larger than the Electron mass. Particular attention is devoted to the $\epsilon$ dependence of radiative corrections.
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structure function method applied to polarized and Unpolarized Electron proton scattering a solution of the g e p g m p discrepancy
Physical Review C, 2007Co-Authors: Yu. M. Bystritskiy, E. A. Kuraev, Egle TomasigustafssonAbstract:The cross section for polarized and Unpolarized Electron-proton scattering is calculated by taking into account radiative corrections in leading and next-to-leading logarithmic approximation. The expression of the cross section is formally similar to the cross section of the Drell-Yan process, where the structure functions of the Electron play the role of Drell-Yan probability distributions. The interference of the Born amplitude with the two-photon exchange amplitude (box-type diagrams) is expressed as a contribution to the K factor. It is calculated under the assumption that proton form factors decrease rapidly with the momentum transfer squared and that the momentum is equally shared between the two photons. The calculation of the box amplitude is done when the intermediate state is the proton or the {delta} resonance. The results of numerical estimations show that the present calculation of radiative corrections can bring into agreement the conflicting experimental results on proton electromagnetic form factors and that the two-photon contribution is very small.
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on radiative corrections for Unpolarized Electron proton elastic scattering
arXiv: High Energy Physics - Phenomenology, 2006Co-Authors: Egle TomasigustafssonAbstract:A statistical analysis of the elastic Unpolarized Electron proton scattering data shows that, at large momentum transfer, the size and the $\epsilon$ dependence of the radiative corrections, as traditionally calculated and applied, may induce large correlations of the parameters of the Rosenbluth fit, which prevent a correct extraction of the electric proton form factor. Using the Electron QED structure (radiation) function approach the cross section of elastic Electron-proton scattering in leading and next-to leading approximations is calculated and expressed as a correction to the Born cross section, which is different for the electric and the magnetic contribution. When properly applied to the data, it may give the solution to the problem of the discrepancy of the polarized and Unpolarized results on Electron proton scattering.
E. A. Kuraev - One of the best experts on this subject based on the ideXlab platform.
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Radiative corrections for Electron-proton elastic scattering taking into account high orders and hard-photon emission
Physical Review C, 2014Co-Authors: E. A. Kuraev, Yu. M. Bystritskiy, A. I. Ahmadov, E. Tomasi-gustafssonAbstract: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 devoted to the $\epsilon$ dependence of radiative corrections, which is directly related to the electric proton form factor. We consider in particular the effects of the interference terms for soft and hard photon emission. Both quadratic amplitude describing the collinear emission along the scattered Electron as well as the interference with the amplitudes of emission from the initial Electron and the emission from protons are important in leading and next to leading approximation and they may compensate in particular kinematical conditions.
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Possible method for measuring the proton form factors in processes with and without proton spin flip
JETP Letters, 2008Co-Authors: M. V. Galynskii, E. A. Kuraev, Yu. M. BystritskiyAbstract:The ratio of the squares of the electric and magnetic proton form factors is shown to be proportional to the ratio of the cross sections for the elastic scattering of an Unpolarized Electron on a partially polarized proton with and without proton spin flip. The initial proton at rest should be polarized along the direction of the motion of the final proton. Similar results are valid for both radiative ep scattering and the photoproduction of pairs on a proton in the Bethe-Heitler kinematics. When the initial proton is fully polarized in the direction of the motion of the final proton, the cross section for the ep → ep process, as well as for the ep → epγ and γp → $$ e\bar ep $$ processes, without (with) proton spin flip is expressed only in terms of the square of the electric (magnetic) proton form factor. Such an experiment on the measurement of the cross sections without and with proton spin flip would make it possible to acquire new independent data on the behavior of G _ E ^2 ( Q ^2) and G _ M ^2 ( Q ^2), which are necessary for resolving the contradictions appearing after the experiment of the JLab collaboration on the measurement of the proton form factors with the method of polarization transfer from the initial Electron to the final proton.
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High order radiative corrections for Unpolarized Electron proton elastic scattering at low $Q^2$
arXiv: High Energy Physics - Phenomenology, 2008Co-Authors: E. A. Kuraev, Yu. M. Bystritskiy, S. Bakmaev, V. V. Bytev, E. Tomasi-gustafssonAbstract: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. We show that higher order terms play a role, starting from values of the momentum transfer squared, $Q^2$, larger than the Electron mass. Particular attention is devoted to the $\epsilon$ dependence of radiative corrections.
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high order radiative corrections for Unpolarized Electron proton elastic scattering at low q 2
arXiv: High Energy Physics - Phenomenology, 2008Co-Authors: E. A. Kuraev, Yu. M. Bystritskiy, S. Bakmaev, V. V. Bytev, Egle TomasigustafssonAbstract: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. We show that higher order terms play a role, starting from values of the momentum transfer squared, $Q^2$, larger than the Electron mass. Particular attention is devoted to the $\epsilon$ dependence of radiative corrections.
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Structure function method applied to polarized and Unpolarized Electron-proton scattering: A solution of the G E ( p ) / G M ( p ) discrepancy
Physical Review C, 2007Co-Authors: Yu. M. Bystritskiy, E. A. Kuraev, E. Tomasi-gustafssonAbstract:The cross section for polarized and Unpolarized Electron-proton scattering is calculated by taking into account radiative corrections in leading and next-to-leading logarithmic approximation. The expression of the cross section is formally similar to the cross section of the Drell-Yan process, where the structure functions of the Electron play the role of Drell-Yan probability distributions. The interference of the Born amplitude with the two-photon exchange amplitude (box-type diagrams) is expressed as a contribution to the K factor. It is calculated under the assumption that proton form factors decrease rapidly with the momentum transfer squared and that the momentum is equally shared between the two photons. The calculation of the box amplitude is done when the intermediate state is the proton or the {delta} resonance. The results of numerical estimations show that the present calculation of radiative corrections can bring into agreement the conflicting experimental results on proton electromagnetic form factors and that the two-photon contribution is very small.
O. Shekhovtsova - One of the best experts on this subject based on the ideXlab platform.
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Radiative corrections to deep inelastic Electron-deuteron scattering: The case of tensor-polarized deuteron
Journal of Experimental and Theoretical Physics, 2004Co-Authors: G. I. Gakh, O. ShekhovtsovaAbstract:Model-independent radiative corrections to deep inelastic scattering of an Unpolarized Electron beam off the tensor-polarized deuteron target are considered. The contribution to the radiative corrections due to the hard photon emission from the elastic Electron-deuteron scattering (the so-called elastic radiative tail) is also investigated. The calculation is based on the covariant parametrization of the deuteron quadrupole polarization tensor. Radiative corrections to the polarization observables are estimated numerically for the kinematical conditions of the current experiment at HERA.
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Radiative events in DIS of Unpolarized Electron by tensor polarized deuteron. Radiative events
arXiv: High Energy Physics - Phenomenology, 2003Co-Authors: G. I. Gakh, O. ShekhovtsovaAbstract:DIS of Unpolarized Electron by tensor-polarized deuteron with tagged collinear photon, radiated from initial Electron, was considered. The cross section is derived in the Born approximation. The model-independent QED corrections to the Born cross section are also calculated using approach based on the account of all essential Feynman diagrams.
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Radiative events in deep-inelastic scattering of Unpolarized Electron by tensor-polarized deuteron. Radiative corrections
2002Co-Authors: G. I. Gakh, O. ShekhovtsovaAbstract:Deep-inelastic scattering (DIS) of unpoladzed Electron by tensor-polarized deuteron with tagged collinear photon, radiated from the initial Electron, is considered. The cross section is derived in the Born approximation. The model-independent QED corrections to the Born cross section are also calculated using an approach based on the account of all essential Feynman diagrams.
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QED CORRECTIONS TO POLARIZED DEEP-INELASTIC AND SEMI-INCLUSIVE DEEP-INELASTIC SCATTERING
2001Co-Authors: G. I. Gakh, N. P. Merenkov, O. ShekhovtsovaAbstract:Leading-log model-independent QED corrections in DIS of Unpolarized Electron off tensor-polarized deuteron are considered. Same approach was used for investigation of semi-inclusive DIS of Electron by nucleus with detection of hadron and scattered Electron. Calculations are based on covariant parametrization of polarization and use of Drell-Yan like representation to describe radiation by initial and scattered Electron. Applications to polarization transfer from polarized Electron to detected hadron and to scattering by polarized target are considered. DIS of Unpolarized Electron on tensor-polarized deuteron with tagged collinear photon radiated from initial-state Electron are investigated. PACS: 12.20.-m, 13.40.-f, 13.60.-Hb, 13.88.+e
