Form Factors and Two-Photon Exchange in High-Energy Elastic Electron-Proton Scattering

Abstract

We present new precision measurements of the elastic electron-proton scattering cross section for momentum transfer (Q${}^2$) up to 15.75~\gevsq. Combined with existing data, these provide an improved extraction of the proton magnetic form factor at high Q${}^2$ and double the range over which a longitudinal/transverse separation of the cross section can be performed. The difference between our results and polarization data agrees with that observed at lower Q${}^2$ and attributed to hard two-photon exchange (TPE) effects, extending to 8~(GeV/c)${}^2$ the range of Q${}^2$ for which a discrepancy is established at $>$95\% confidence. We use the discrepancy to quantify the size of TPE contributions needed to explain the cross section at high Q${}^2$.

7 pages, 2 figures

References in corpus (12)

• Global analysis of proton elastic form factor data with two-photon exchange corrections
• Proton and neutron electromagnetic form factors and uncertainties
• Diquark Correlations in Hadron Physics: Origin, Impact and Evidence
• Measurement of the proton electric to magnetic form factor ratio from \vec ^1H(\vec e, e'p)
• Measurement of the two-photon exchange contribution to the elastic $e^{\pm }p$ scattering cross sections at the VEPP-3 storage ring
• Polarization Transfer in the 4He(e,e'p)3H Reaction at Q^2 = 0.8 and 1.3 (GeV/c)^2
• Towards a resolution of the proton form factor problem: new electron and positron scattering data
• Search for effects beyond the Born approximation in polarization transfer observables in $\vec{e}p$ elastic scattering
• Hard Two-Photon Contribution to Elastic Lepton-Proton Scattering: Determined by the OLYMPUS Experiment
• Proton G_E/G_M from beam-target asymmetry
• Is there model-independent evidence of the two-photon-exchange effect in the electron-proton elastic scattering cross section?
• On radiative corrections to polarization observables in electron-proton scattering

Cited by in corpus (10)

• 50 Years of Quantum Chromodynamics
• The Present and Future of QCD
• Impact of JLab data on the determination of GPDs at zero skewness and new insights from transition form factors $N\to \Delta$
• Understanding the systematic differences in extractions of the proton electric form factors at low-$Q^2$
• Electromagnetic nucleon form factors in the extended vector meson dominance model
• A novel approach to the global analysis of proton form factors in elastic electron-proton scattering
• Impact of new particles on the ratio of Electromagnetic form factors
• Resonance Contributions to Radiative Corrections in Charged-Current Elastic (Anti)Neutrino-Nucleon Scattering at GeV Energies
• Exploring Nucleon Structure and the Proton Mass Problem through Holographic QCD
• Global Analyses of Generalized Parton Distributions with Diverse PDF Inputs