Two Photon Exchange Contributions to Elastic ep Scattering in the Nonlocal Field Formalism

Abstract

We construct a nonlocal gauge invariant Lagrangian to model the electromagnetic interaction of proton. The Lagrangian includes all allowed operators with dimension up to five. We compute the two photon exchange contribution to elastic electron-proton scattering using this effective nonlocal Lagrangian. The one loop calculation in this model includes the standard box and cross box diagram with the standard on-shell form of the hadron electromagnetic vertices. Besides this we find an extra contribution which depends on an unknown constant. We use experimentally extracted form factors for our calculation. We find that the correction to the reduced cross section is slightly nonlinear as a function of the photon longitudinal polarization $\epsilon$. The non-linearity seen is within the experimental error bars of the Rosenbluth data. The final result completely explains the difference between the form factor ratio $G_E/G_M$ extracted by Rosenbluth separation technique at SLAC and polarization transfer technique at JLAB.

arXiv comment39 pages, 16 figures

References in corpus (14)

• The ratio of proton's electric to magnetic form factors measured by polarization transfer
• Measurement of GEp/GMp in ep -> ep to Q2 = 5.6 GeV2
• Proton elastic form factor ratios to $Q^2$ = 3.5 GeV${}^2$ by polarization transfer
• Dispersion-Theoretical Analysis of the Nucleon Electromagnetic Formfactors
• Two-photon exchange and elastic electron-proton scattering
• How to reconcile the Rosenbluth and the polarization transfer method in the measurement of the proton form factors
• Precision Rosenbluth measurement of the proton elastic form factors
• Dispersion analysis of the nucleon form factors including meson continua
• Two-photon exchange in elastic electron-nucleon scattering
• Radiative Corrections to Electron-Proton Scattering
• The two-photon exchange contribution to elastic electron-nucleon scattering at large momentum transfer
• Model independent properties of two-photon exchange in elastic electron proton scattering
• Extraction of two-photon contributions to the proton form factors
• Nonlocal Yang-Mills

Cited by in corpus (3)

• Nucleon electromagnetic form factors
• Two Photon Exchange Contributions to Elastic e + p --> e + p Process in a Nonlocal Field Formalism
• Two-photon contributions to the Rosenbluth cross-section in the Skyrme model