Polarization Transfer Observables in Elastic Electron Proton Scattering at $Q^2=$2.5, 5.2, 6.8, and 8.5 GeV${}^2$

Abstract

The GEp-III and GEp-2$\gamma$ experiments were carried out in Jefferson Lab's (JLab's) Hall C from 2007-2008, to extend the knowledge of $G_E^p/G_M^p$ to the highest practically achievable $Q^2$ and to search for effects beyond the Born approximation in polarization transfer observables of elastic $\vec{e}p$ scattering. This article reports an expanded description of the common experimental apparatus and data analysis procedure, and the results of a final reanalysis of the data from both experiments, including the previously unpublished results of the full-acceptance data of the GEp-2$\gamma$ experiment. The Hall C High Momentum Spectrometer detected and measured the polarization of protons recoiling elastically from collisions of JLab's polarized electron beam with a liquid hydrogen target. A large-acceptance electromagnetic calorimeter detected the elastically scattered electrons in coincidence to suppress inelastic backgrounds. The final GEp-III data are largely unchanged relative to the originally published results. The statistical uncertainties of the final GEp-2$\gamma$ data are significantly reduced at $\epsilon =0.632$ and $0.783$ relative to the original publication. The decrease with $Q^2$ of $G_E^p/G_M^p$ continues to $Q^2=8.5$ GeV${}^2$, but at a slowing rate relative to the approximately linear decrease observed in earlier Hall A measurements. At $Q^2=2.5$ GeV${}^2$, the proton form factor ratio $G_E^p/G_M^p$ shows no statistically significant $\epsilon$-dependence, as expected in the Born approximation. The ratio $P_{\ell }/P_{\ell }^{Born}$ of the longitudinal polarization transfer component to its Born value shows an enhancement of roughly 1.4\% at $\epsilon =0.783$ relative to $\epsilon =0.149$, with $\approx 1.9\sigma$ significance based on the total uncertainty, implying a similar effect in the transverse component $P_t$ that cancels in the ratio $R$.

arXiv comment44 pages, 28 figures. Archival publication for the GEp-III and GEp-2gamma experiments that ran in Jefferson Lab's experimental Hall C from October, 2007 to June, 2008. v2: final manuscript as accepted by PRC. v3: Replaced figures 13 and 19 with corrected versions from published Erratum. Also made minor corrections to the text and to Table XI reflecting the corrections in the published Erratum

References in corpus (104)

• Gauge-Invariant Decomposition of Nucleon Spin and Its Spin-Off
• Generalized Parton Distributions
• Unraveling hadron structure with generalized parton distributions
• Hard Exclusive Reactions and the Structure of Hadrons
• 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
• Impact Parameter Space Interpretation for Generalized Parton Distributions
• Off-Forward Parton Distributions
• Nucleon Electromagnetic Form Factors
• Proton elastic form factor ratios to $Q^2$ = 3.5 GeV${}^2$ by polarization transfer
• 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
• Unified description of light- and strange-baryon spectra
• Charge Density of the Neutron
• Explanation and Prediction of Observables using Continuum Strong QCD
• Nucleon Form Factors from Generalized Parton Distributions
• Precision Rosenbluth measurement of the proton elastic form factors
• Recoil Polarization Measurements of the Proton Electromagnetic Form Factor Ratio to Q^2 = 8.5 GeV^2
• Generalized parton distributions from nucleon form factor data
• Two-photon exchange in elastic electron-nucleon scattering
• Nucleon electromagnetic form factors
• Generalized Parton Distributions in the valence region from Deeply Virtual Compton Scattering
• Measurements of electron-proton elastic cross sections for $0.4<Q^2<5.5(GeV/c{)}^2$
• High Precision Measurement of the Proton Elastic Form Factor Ratio ${\mu }_p{G}_E/G_M$ at low $Q^2$
• The two-photon exchange contribution to elastic electron-nucleon scattering at large momentum transfer
• Perturbative QCD Analysis of the Nucleon's Pauli Form Factor F_2(Q^2)
• Nucleon Form Factors in QCD
• Review of two-photon exchange in electron scattering
• Final Analysis of Proton Form Factor Ratio Data at ${\mathbf{Q}}^2=4.0$, 4.8 and 5.6 GeV${}^2$
• Study of e+e- --> p anti-p via initial-state radiation at BABAR
• Electromagnetic Form Factors of the Nucleon and Compton Scattering
• Two-Photon Physics in Hadronic Processes
• Light Front Cloudy Bag Model: Nucleon Electromagnetic Form Factors
• Flavor decomposition of the elastic nucleon electromagnetic form factors
• Nucleon form factors, generalized parton distributions and quark angular momentum
• Nucleon and pion electromagnetic form factors in a light-front constituent quark model
• Survey of nucleon electromagnetic form factors
• Transverse Charge Densities
• $\Delta$ resonance contribution to two-photon exchange in electron-proton scattering
• Measurements of the Electric Form Factor of the Neutron up to Q2=3.4 GeV2 using the Reaction He3(e,e'n)pp
• QED radiative corrections to virtual Compton scattering
• Nucleon and $\Delta$ elastic and transition form factors
• 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
• The Role of Color Neutrality in Nuclear Physics--Modifications of Nucleonic Wave Functions
• Effective Q-Q Interactions in Constituent Quark Models
• Relativistic Constituent Quark Model of Electroweak Properties of Baryons
• Two-photon exchange in elastic electron-proton scattering
• Re-analysis of the nucleon space- and time-like electromagnetic form factors in a two-component model
• Polarization Transfer in the 4He(e,e'p)3H Reaction at Q^2 = 0.8 and 1.3 (GeV/c)^2
• Effect of recent R_p and R_n measurements on extended Gari-Krumpelmann model fits to nucleon electromagnetic form factors
• Measurement of the vector analyzing power in elastic electron-proton scattering as a probe of double photon exchange amplitudes
• Status on nucleon electromagnetic form factors
• New empirical fits to the proton electromagnetic form factors
• Low Q^2 measurements of the proton form factor ratio $m{u}_p{G}_E/G_M$
• 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
• Measurement of the Transverse Beam Spin Asymmetry in Elastic Electron Proton Scattering and the Inelastic Contribution to the Imaginary Part of the Two-Photon Exchange Amplitude
• Hard Two-Photon Contribution to Elastic Lepton-Proton Scattering: Determined by the OLYMPUS Experiment
• Realistic Transverse Images of the Proton Charge and Magnetic Densities
• Evidence for two-photon exchange contributions in electron-proton and positron-proton elastic scattering
• $Q^2$ Independence of $Q{F}_2/F_1$, Poincare Invariance and the Non-Conservation of Helicity
• A pure S-wave covariant model for the nucleon
• Extended Gari-Krumpelmann model fits to nucleon electromagnetic form factors
• Structure of the nucleon from electromagnetic space-like and time-like form factors
• A Comparison of Polarization Observables in Electron Scattering from the Proton and Deuteron
• Two-photon exchange in elastic electron-proton scattering : QCD factorization approach
• The Proton Radius from Electron Scattering Data
• Nucleon electromagnetic form factors in twisted mass lattice QCD
• The covariant structure of light-front wave functions and the behavior of hadronic form factors
• Nucleon electromagnetic form factors in two-flavour QCD
• Flavor decomposition of the nucleon electromagnetic form factors
• The structure function method applied to polarized and unpolarized electron-proton scattering: a solution of the G_E(p)/G_M(p) discrepancy
• Experimental constraints on non-linearities induced by two-photon effects in elastic and inelastic Rosenbluth separations
• Magnetic form factors of the octet baryons from lattice QCD and chiral extrapolation
• Measurement of two-photon exchange effect by comparing elastic $e^{\pm }p$ cross sections
• New Measurements of the Transverse Beam Asymmetry for Elastic Electron Scattering from Selected Nuclei
• Time- and Spacelike Nucleon Electromagnetic Form Factors beyond Relativistic Constituent Quark Models
• A dispersive approach to two-photon exchange in elastic electron-proton scattering
• Nucleon Form Factors and Distribution Amplitudes in QCD
• Dirac and Pauli form factors from lattice QCD
• Electric form factors of the octet baryons from lattice QCD and chiral extrapolation
• Nucleon Form Factors in a Relativistic Quark Model
• Two-photon exchange corrections to elastic electron-proton scattering at large momentum transfer within the SCET approach
• Determination of two-photon exchange amplitudes from elastic electron-proton scattering data
• Model independent radiative corrections in processes of polarized electron-nucleon elastic scattering
• The Proton Elastic Form Factor Ratio at Low Momentum Transfer
• Time-like and space-like electromagnetic form factors of nucleons, a unified description
• Two photon exchange amplitude with πN intermediate states: P33 channel
• Nucleon Form Factors - A Jefferson Lab Perspective
• QCD Form Factors and Hadron Helicity Non-Conservation
• Transverse Beam Spin Asymmetries in Forward-Angle Elastic Electron-Proton Scattering
• The shape of the nucleon
• Soft spectator scattering in the nucleon form factors at large $Q^2$ within the SCET approach
• Transverse Beam Spin Asymmetries at Backward Angles in Elastic Electron-Proton and Quasi-elastic Electron-Deuteron Scattering
• QED Radiative Corrections to Asymmetries of Elastic ep-scattering in Hadronic Variables
• Measurement of the Target-Normal Single-Spin Asymmetry in Quasi-Elastic Scattering from the Reaction ${}^3$He${}^{\uparrow }(e,e^{\prime })$
• A light-front description of electromagnetic form factors for $J\le 3/2$ hadrons
• High $Q^2$ behavior of the electromagnetic form factors in the relativistic hypercentral CQM
• Radiative Correction to the Transferred Polarization in Elastic Electron-Proton Scattering
• Monte Carlo generator ELRADGEN 2.0 for simulation of radiative events in elastic ep-scattering of polarized particles
• Polarization components in ${\pi }^0$ photoproduction at photon energies up to 5.6 GeV
• Elastic nucleon form factors
• Beam Normal Single Spin Asymmetry Measurements from QWeak

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• An experimental program with high duty-cycle polarized and unpolarized positron beams at Jefferson Lab
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• Determination of the generalized parton distributions through the analysis of the world electron scattering data considering two-photon exchange corrections
• Nucleon relativistic polarization and magnetization distributions
• Electromagnetic properties of the nucleon and the Roper resonance in soft-wall AdS/QCD at finite temperature
• New evaluation of axial nucleon form factor from electron- and neutrino-scattering data and impact on neutrino-nucleus cross-section
• Hadronic Footprint of GeV-Mass Dark Matter
• Lepton-Flavor-Violating ALP Signals with TeV-Scale Muon Beams
• Toy model to understand oscillatory behavior in timelike nucleon form factors
• Electromagnetic form factors of the ${\Omega }^{-}$ baryon in the spacelike and timelike regions
• Proton Electromagnetic Form Factors in the Time-like Region through the Scan Technique
• Proton Form Factor Ratio, ${\mu }_p{G}_E^p/G_M^p$ from Double Spin Asymmetry
• Electromagnetic $|G_E/G_M|$ ratios of hyperons at large timelike $q^2$
• Low-$Q^2$ empirical parametrizations of the $N^{\ast }$ helicity amplitudes
• Updated analysis of recent results on electron and positron elastic scattering on proton
• Design and Performance of the Spin Asymmetries of the Nucleon Experiment
• Model independent radiative corrections to elastic deuteron-electron scattering
• Unraveling sub-leading twist GTMDs of proton using LFQDM
• Two-photon exchange: myth and history
• Two photon exchange in elastic electron scattering off hadronic systems
• Generalized Sachs Form Factors and the Possibility of Their Measurement in Processes without and with Proton Spin Flip
• Parity-Violating Inelastic Electron-Proton Scattering at Low $Q^2$ Above the Resonance Region
• Polarization transfer in ${\vec{e}}^{+}p\to e^{+}\vec{p}$ scattering using the Super BigBite Spectrometer
• Electromagnetic nucleon form factors in the extended vector meson dominance model
• Search for damped oscillating structures from charged pion electromagnetic form factor data
• Electroweak form factors of baryons in dense nuclear matter
• On the Transfer of Polarization from the Initial to the Final Proton in the Elastic Process $e\vec{p}\to e\vec{p}$
• Angular Dependence of the Polarization Transfer to the Proton in the $e\vec{p}\to e\vec{p}$ Process
• Unraveling the structure of $\Lambda$ hyperons with polarized $\Lambda \bar{\Lambda }$ pairs
• Technical Supplement to "Polarization Transfer Observables in Elastic Electron-Proton Scattering at Q${}^2$ = 2.5, 5.2, 6.8, and 8.5 GeV${}^2$"
• Polarization Observables using Positron Beams
• 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
• Radiative corrections in proton--antiproton annihilation to electron-positron and their application to the PANDA experiment
• Direct TPE Measurement via $e^{+}p/e^{-}p$ Scattering at low $\epsilon$ in Hall A
• A measurement of two-photon exchange in Super-Rosenbluth separations with positron beams
• Super-Rosenbluth Measurements with Electrons and Positrons
• Prediction of neutron electromagnetic form factors behaviors just by the proton electromagnetic form factors data
• Axial meson contribution to proton form factors
• Theory of QED radiative corrections to neutrino scattering at accelerator energies