Nucleon Form Factors - A Jefferson Lab Perspective

Abstract

The charge and magnetization distributions of the proton and neutron are encoded in their elastic electromagnetic form factors, which can be measured in elastic electron--nucleon scattering. By measuring the form factors, we probe the spatial distribution of the proton charge and magnetization, providing the most direct connection to the spatial distribution of quarks inside the proton. For decades, the form factors were probed through measurements of unpolarized elastic electron scattering, but by the 1980s, progress slowed dramatically due to the intrinsic limitations of the unpolarized measurements. Early measurements at several laboratories demonstrated the feasibility and power of measurements using polarization degrees of freedom to probe the spatial structure of the nucleon. A program of polarization measurements at Jefferson Lab led to a renaissance in the field of study, and significant new insight into the structure of matter.

20 pages, 9 figures; Chapter in the book "A decade of Physics at Jefferson Lab", to be published in Journal of Physics: Conference Series

References in corpus (61)

• New Generation of Parton Distributions with Uncertainties from Global QCD Analysis
• 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
• High-precision determination of the electric and magnetic form factors of the proton
• 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
• Quark Imaging in the Proton Via Quantum Phase-Space Distributions
• Global analysis of proton elastic form factor data with two-photon exchange corrections
• Charge Density of the Neutron
• 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
• Partonic calculation of the two-photon exchange contribution to elastic electron-proton scattering at large momentum transfer
• Two-photon exchange in elastic electron-nucleon scattering
• Nucleon electromagnetic form factors
• Measurements of electron-proton elastic cross sections for $0.4<Q^2<5.5(GeV/c{)}^2$
• A Coherent Interpretation of the Form Factors of the Nucleon in Terms of a Pion Cloud and Constituent Quarks
• Precise Neutron Magnetic Form Factors
• Radiative Corrections to Electron-Proton Scattering
• 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)
• How well do we know the electromagnetic form factors of the proton?
• Measurements of GEn/GMn from the ^2H(vec{e},e'vec{n})^1H Reaction to Q^2=1.45 (GeV/c)^2
• Measurement of the Electric Form Factor of the Neutron at Q^2=0.5 and 1.0 (GeV/c)^2
• Electromagnetic Form Factors of the Nucleon and Compton Scattering
• Two-Photon Physics in Hadronic Processes
• The Transverse Asymmetry ${\mathbf{A}}_{{\mathbf{T}}^{\prime }}$ from Quasi-elastic ${}^3\overrightarrow{\mathrm{He}}(\vec{e},e^{\prime })$ Process and the Neutron Magnetic Form Factor
• Light Front Cloudy Bag Model: Nucleon Electromagnetic Form Factors
• Nucleon Charge and Magnetization Densities from Sachs Form Factors
• Survey of nucleon electromagnetic form factors
• Implications of the discrepancy between proton form factor measurements
• Extraction of electromagnetic neutron form factors through inclusive and exclusive polarized electron scattering on polarized 3He target
• Polarization Transfer in the ^4He(\vec e,e'\vec p)^3H Reaction up to Q^2 = 2.6 (GeV/c)^2
• Measurements of the Electric Form Factor of the Neutron up to Q2=3.4 GeV2 using the Reaction He3(e,e'n)pp
• Neutron charge form factor at large $q^2$
• Measurement of the proton electric to magnetic form factor ratio from \vec ^1H(\vec e, e'p)
• Coulomb Corrections to Elastic Electron-Proton Scattering and the Proton Charge Radius
• 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
• A Precise Measurement of the Neutron Magnetic Form Factor GMn in the Few-GeV2 Region
• Realistic Transverse Images of the Proton Charge and Magnetic Densities
• Measurements of the neutron electric to magnetic form factor ratio GEn/GMn via the ^2H(\vec{e},e'\vec{n})^1H reaction to Q^2 = 1.45 (GeV/c)^2
• Evidence for two-photon exchange contributions in electron-proton and positron-proton elastic scattering
• Proton radii and two-photon exchange
• PWIA Extraction of the Neutron Magnetic Form Factor from Quasi-Elastic 3He(e,e') at Q^2 = 0.3 to 0.6 (GeV/c)^2
• Extraction of two-photon contributions to the proton form factors
• Updated dispersion-theoretical analysis of the nucleon electromagnetic form factors
• The Charge Form Factor of the Neutron at Low Momentum Transfer from the ${}^2\vec{\mathrm{H}}(\vec{\mathrm{e}},{\mathrm{e}}^{\prime }\mathrm{n})\mathrm{p}$ Reaction
• 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
• Extraction of the Neutron Magnetic Form Factor from Quasi-Elastic 3He(pol)(e(pol),e') at Q^2 = 0.1 - 0.6 (GeV/c)^2
• Contribution of spin 1/2 and 3/2 resonances to two-photon exchange effects in elastic electron-proton scattering
• Shapes of the Proton
• Model independent radiative corrections in processes of polarized electron-nucleon elastic scattering
• The Proton Elastic Form Factor Ratio at Low Momentum Transfer
• Polarization transfer in ${}^4$He$(\vec{e},e^{\prime }\vec{p})$${}^3$H: is the ratio $G_{Ep}/G_{Mp}$ modified in medium ?
• The neutron negative central charge density: an inclusive-exclusive connection
• Origin of Relativistic Effects in the Reaction D(e,e'p)n at GeV Energies
• Radiative Correction to the Transferred Polarization in Elastic Electron-Proton Scattering

Cited by in corpus (25)

• Baryons as relativistic three-quark bound states
• Muonic hydrogen and the proton radius puzzle
• High Precision Measurement of the Proton Elastic Form Factor Ratio ${\mu }_p{G}_E/G_M$ at low $Q^2$
• Review of two-photon exchange in electron scattering
• Proton and neutron electromagnetic form factors and uncertainties
• 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
• Polarization Transfer Observables in Elastic Electron Proton Scattering at $Q^2=$2.5, 5.2, 6.8, and 8.5 GeV${}^2$
• New insights into the nucleon's electromagnetic structure
• Nucleon Electromagnetic Form Factors in the Timelike Region
• Flavor decomposition of the nucleon electromagnetic form factors
• Nucleon form factors and spin content in a quark-diquark model with a pion cloud
• Dirac and Pauli form factors from lattice QCD
• Magnetic and quadrupole moments of the $Z_c(3900)$
• Chiral extrapolations for nucleon electric charge radii
• Chiral extrapolations for nucleon magnetic moments
• Demonstration of a novel technique to measure two-photon exchange effects in elastic $e^{\pm }p$ scattering
• Polarization of the final nucleon in quasi-elastic neutrino scattering and the axial form factor of the nucleon
• On the polarization of the final nucleon in NC elastic ν_μ(\barν_μ) - N scattering
• Up- and down-quark contributions to the nucleon electromagnetic form factors at low $Q^2$
• Proton and neutron form factors from deformed gravity/gauge duality
• Polarized Lepton-Nucleon Elastic Scattering and a Search for a Light Scalar Boson
• A measurement of two-photon exchange in Super-Rosenbluth separations with positron beams
• Baryon Form Factors
• A novel measurement of the neutron magnetic form factor from A=3 mirror nuclei