skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Flavor decomposition of the nucleon electromagnetic form factors at low Q 2

Abstract

Background: The spatial distribution of charge and magnetization within the proton is encoded in the elastic form factors. These have been precisely measured in elastic electron scattering, and the combination of proton and neutron form factors allows for the separation of the up- and down-quark contributions. Purpose: In this work, we extract the proton and neutron form factors from worldwide data with an emphasis on precise new data covering the low-momentum region, which is sensitive to the large-scale structure of the nucleon. From these, we separate the up- and down-quark contributions to the proton form factors. Method: We combine cross section and polarization measurements of elastic electron-proton scattering to separate the proton form factors and two-photon exchange (TPE) contributions. We combine the proton form factors with parametrization of the neutron form factor data and uncertainties to separate the up- and down-quark contributions to the proton's charge and magnetic form factors. Results: The extracted TPE corrections are compared to previous phenomenological extractions, TPE calculations, and direct measurements from the comparison of electron and positron scattering. The flavor-separated form factors are extracted and compared to models of the nucleon structure. Conclusions: With the inclusion of the precise new data, the extracted TPEmore » contributions show a clear change of sign at low Q(2), which is necessary to explain the high-Q(2) form factor discrepancy while being consistent with the known Q(2) -> 0 limit. We find that the new Mainz data yield a significantly different result for the proton magnetic form factor and its flavor-separated contributions. We also observe that the rms radius of both the up- and down-quark distributions are smaller than the rms charge radius of the proton.« less

Authors:
; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science - Office of Nuclear Physics
OSTI Identifier:
1392107
DOE Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article
Journal Name:
Physical Review. C, Nuclear Physics
Additional Journal Information:
Journal Volume: 91; Journal Issue: 6; Journal ID: ISSN 0556-2813
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English

Citation Formats

Qattan, I. A., Arrington, J., and Alsaad, A. Flavor decomposition of the nucleon electromagnetic form factors at low Q2. United States: N. p., 2015. Web. doi:10.1103/PhysRevC.91.065203.
Qattan, I. A., Arrington, J., & Alsaad, A. Flavor decomposition of the nucleon electromagnetic form factors at low Q2. United States. doi:10.1103/PhysRevC.91.065203.
Qattan, I. A., Arrington, J., and Alsaad, A. Mon . "Flavor decomposition of the nucleon electromagnetic form factors at low Q2". United States. doi:10.1103/PhysRevC.91.065203.
@article{osti_1392107,
title = {Flavor decomposition of the nucleon electromagnetic form factors at low Q2},
author = {Qattan, I. A. and Arrington, J. and Alsaad, A.},
abstractNote = {Background: The spatial distribution of charge and magnetization within the proton is encoded in the elastic form factors. These have been precisely measured in elastic electron scattering, and the combination of proton and neutron form factors allows for the separation of the up- and down-quark contributions. Purpose: In this work, we extract the proton and neutron form factors from worldwide data with an emphasis on precise new data covering the low-momentum region, which is sensitive to the large-scale structure of the nucleon. From these, we separate the up- and down-quark contributions to the proton form factors. Method: We combine cross section and polarization measurements of elastic electron-proton scattering to separate the proton form factors and two-photon exchange (TPE) contributions. We combine the proton form factors with parametrization of the neutron form factor data and uncertainties to separate the up- and down-quark contributions to the proton's charge and magnetic form factors. Results: The extracted TPE corrections are compared to previous phenomenological extractions, TPE calculations, and direct measurements from the comparison of electron and positron scattering. The flavor-separated form factors are extracted and compared to models of the nucleon structure. Conclusions: With the inclusion of the precise new data, the extracted TPE contributions show a clear change of sign at low Q(2), which is necessary to explain the high-Q(2) form factor discrepancy while being consistent with the known Q(2) -> 0 limit. We find that the new Mainz data yield a significantly different result for the proton magnetic form factor and its flavor-separated contributions. We also observe that the rms radius of both the up- and down-quark distributions are smaller than the rms charge radius of the proton.},
doi = {10.1103/PhysRevC.91.065203},
journal = {Physical Review. C, Nuclear Physics},
issn = {0556-2813},
number = 6,
volume = 91,
place = {United States},
year = {2015},
month = {6}
}

Works referenced in this record:

Two-Photon Exchange and Elastic Electron-Proton Scattering
journal, October 2003


Two-photon exchange at low Q 2
journal, March 2007


Strange-Quark Contributions to Parity-Violating Asymmetries in the Forward G0 Electron-Proton Scattering Experiment
journal, August 2005


Explanation and prediction of observables using continuum strong QCD
journal, July 2014


Determination of two-photon exchange amplitudes from elastic electron-proton scattering data
journal, June 2011


Recoil Polarization Measurements of the Proton Electromagnetic Form Factor Ratio to Q 2 = 8.5 GeV 2
journal, June 2010


The spin and flavor dependence of parton distribution functions
journal, September 1988


Scattering of positrons and electrons from protons
journal, August 1967


Electromagnetic form factors of the proton at squared four-momentum transfers between 10 and 50 fm−2
journal, April 1971


P ARITY -V IOLATING E LECTRON S CATTERING AND N UCLEON S TRUCTURE
journal, December 2001


New Precision Limit on the Strange Vector Form Factors of the Proton
journal, March 2012


Backward scattering of positrons and electrons on protons
journal, January 1968


Publisher's Note: Proton elastic form factor ratios to Q 2 = 3.5 GeV 2 by polarization transfer [Phys. Rev. C 71, 055202 (2005)]
journal, June 2005


Proton G E / G M from beam-target asymmetry
journal, September 2006


Comparison of Elastic Positron-Proton and Electron-Proton Scattering Cross Sections
journal, November 1967


Interpretation of the flavor dependence of nucleon form factors in a generalized parton distribution model
journal, December 2013

  • Gonzalez-Hernandez, J. Osvaldo; Liuti, Simonetta; Goldstein, Gary R.
  • Physical Review C, Vol. 88, Issue 6
  • DOI: 10.1103/PhysRevC.88.065206

How to Reconcile the Rosenbluth and the Polarization Transfer Methods in the Measurement of the Proton Form Factors
journal, October 2003


Precision Rosenbluth Measurement of the Proton Elastic Form Factors
journal, April 2005


The ratio of proton electromagnetic form factors via recoil polarimetry at
journal, January 2006


Search for Effects Beyond the Born Approximation in Polarization Transfer Observables in e p Elastic Scattering
journal, March 2011


Reexamination of phenomenological two-photon exchange corrections to the proton form factors and e ± p scattering
journal, November 2011


Two-Photon Exchange in Elastic Electron-Proton Scattering: A QCD Factorization Approach
journal, August 2009


Measurements of electron-proton elastic cross sections for 0.4 < Q 2 < 5.5 ( GeV c ) 2
journal, July 2004


Measurement of the ratio of the proton form factors, GE/GM, at high momentum transfers and the question of scaling
journal, January 1970


How well do we know the electromagnetic form factors of the proton?
journal, September 2003


Proton elastic form factor ratios to Q 2 = 3.5 GeV 2 by polarization transfer
journal, May 2005


Measurements of the proton elastic form factors for 1 Q 2 3 ( G e V / c ) 2 at SLAC
journal, June 1994


Comparison of Electron-Proton and Positron-Proton Elastic Scattering at Four-Momentum Transfers up to 5.0 ( G e V / c ) 2
journal, August 1968


Polarization Transfer in the He 4 ( e , e p ) H 3 Reaction at Q 2 = 0.8 and 1.3 ( GeV / c ) 2
journal, August 2010


Δ Resonance Contribution to Two-Photon Exchange in Electron-Proton Scattering
journal, October 2005


Measurements of the electric and magnetic form factors of the proton from Q 2 =1.75 to 8.83 (GeV/ c ) 2
journal, November 1994


Proton Structure from the Measurement of 2S-2P Transition Frequencies of Muonic Hydrogen
journal, January 2013


Two-photon exchange in elastic electron-nucleon scattering
journal, September 2005


Polarization transfer in elastic electron scattering from nucleons and deuterons
journal, January 1981

  • Arnold, Raymond G.; Carlson, Carl E.; Gross, Franz
  • Physical Review C, Vol. 23, Issue 1
  • DOI: 10.1103/PhysRevC.23.363

Coulomb corrections in the extraction of the proton radius
journal, October 2013


Partonic Calculation of the Two-Photon Exchange Contribution to Elastic Electron-Proton Scattering at Large Momentum Transfer
journal, September 2004


Proton Form Factors from Elastic Electron-Proton Scattering
journal, February 1966


Review of two-photon exchange in electron scattering
journal, October 2011

  • Arrington, J.; Blunden, P. G.; Melnitchouk, W.
  • Progress in Particle and Nuclear Physics, Vol. 66, Issue 4
  • DOI: 10.1016/j.ppnp.2011.07.003

Role of diquark correlations and the pion cloud in nucleon elastic form factors
journal, October 2014


Measurement of G E p / G M p in e p e p to Q 2 = 5.6 GeV 2
journal, February 2002


Polarization Transfer in the H e 4 ( e , e p ) H 3 Reaction up to Q 2 = 2.6     ( G e V / c ) 2
journal, July 2003


Survey of Nucleon Electromagnetic Form Factors
journal, March 2009


Measurement of the Two-Photon Exchange Contribution to the Elastic e ± p Scattering Cross Sections at the VEPP-3 Storage Ring
journal, February 2015


Experimental constraints on nonlinearities induced by two-photon effects in elastic and inelastic Rosenbluth separations
journal, February 2006


Strange Quark Contributions to Parity-Violating Asymmetries in the Backward Angle G0 Electron Scattering Experiment
journal, January 2010


Towards a Resolution of the Proton Form Factor Problem: New Electron and Positron Scattering Data
journal, February 2015


Nucleon electromagnetic form factors
journal, May 2007

  • Arrington, J.; Roberts, C. D.; Zanotti, J. M.
  • Journal of Physics G: Nuclear and Particle Physics, Vol. 34, Issue 7
  • DOI: 10.1088/0954-3899/34/7/S03

Electric and magnetic form factors of the proton
journal, July 2014


Is there model-independent evidence of the two-photon-exchange effect in the electron–proton elastic scattering cross section?
journal, September 2007


Strange Vector Form Factors from Parity-Violating Electron Scattering
journal, May 2011


Two-photon exchange in a dispersion approach
journal, August 2008


Nucleon electromagnetic form factors
journal, October 2007

  • Perdrisat, C. F.; Punjabi, V.; Vanderhaeghen, M.
  • Progress in Particle and Nuclear Physics, Vol. 59, Issue 2
  • DOI: 10.1016/j.ppnp.2007.05.001

Measurement of the Proton’s Electric to Magnetic Form Factor Ratio from H 1 ( e , e p )
journal, January 2007


Positron-Proton Elastic Scattering at 800 and 1200 MeV
journal, February 1968


High-precision measurement of the proton elastic form factor ratio <mml:math altimg="si1.gif" overflow="scroll" xmlns:xocs="http://www.elsevier.com/xml/xocs/dtd" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.elsevier.com/xml/ja/dtd" xmlns:ja="http://www.elsevier.com/xml/ja/dtd" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:tb="http://www.elsevier.com/xml/common/table/dtd" xmlns:sb="http://www.elsevier.com/xml/common/struct-bib/dtd" xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:cals="http://www.elsevier.com/xml/common/cals/dtd"><mml:msub><mml:mi>μ</mml:mi><mml:mi>p</mml:mi></mml:msub><mml:msub><mml:mi>G</mml:mi><mml:mi>E</mml:mi></mml:msub><mml:mo stretchy="false">/</mml:mo><mml:msub><mml:mi>G</mml:mi><mml:mi>M</mml:mi></mml:msub></mml:math> at low <mml:math altimg="si2.gif" overflow="scroll" xmlns:xocs="http://www.elsevier.com/xml/xocs/dtd" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.elsevier.com/xml/ja/dtd" xmlns:ja="http://www.elsevier.com/xml/ja/dtd" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:tb="http://www.elsevier.com/xml/common/table/dtd" xmlns:sb="http://www.elsevier.com/xml/common/struct-bib/dtd" xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:cals="http://www.elsevier.com/xml/common/cals/dtd"><mml:msup><mml:mi>Q</mml:mi><mml:mn>2</mml:mn></mml:msup></mml:math>
journal, November 2011


Nucleon quark distributions in a covariant quark–diquark model
journal, August 2005


Erratum: Comparison of Polarization Observables in Electron Scattering from the Proton and Deuteron [Phys. Rev. Lett. 80, 452 (1998)]
journal, March 1999


Positron-Proton Scattering
journal, August 1965


Comparison of Polarization Observables in Electron Scattering from the Proton and Deuteron
journal, January 1998


Charge symmetry, quarks and mesons
journal, October 1990


Simple parametrization of nucleon form factors
journal, December 2004


Two-photon exchange amplitudes for elastic e p scattering at Q 2 = 2.5 GeV 2 from experimental data
journal, March 2011


Implications of the discrepancy between proton form factor measurements
journal, February 2004


Low- Q 2 measurements of the proton form factor ratio μ p G E / G M
journal, November 2011


Scattering of Positrons and Electrons from Protons
journal, August 1966


Measurements of the elastic electromagnetic form factor ratio μ p G Ep / G Mp via polarization transfer
journal, August 2001


Demonstration of a novel technique to measure two-photon exchange effects in elastic e ± p scattering
journal, August 2013


Two-Photon Physics in Hadronic Processes
journal, November 2007


Nucleon form factors and spin content in a quark-diquark model with a pion cloud
journal, July 2012


Precise Determination of the Strangeness Magnetic Moment of the Nucleon
journal, June 2005


Box diagram in the elastic electron-proton scattering
journal, December 2006


High Energy Elastic Scattering of Electrons on Protons
journal, August 1950


Scattering of High-Energy Positrons from Protons
journal, November 1962


Electromagnetic form factors of the nucleon: New fit and analysis of uncertainties
journal, June 2009


Realistic transverse images of the proton charge and magnetization densities
journal, January 2011


Parity-violating electroweak asymmetry in e p scattering
journal, June 2004


Extended Gari-Krümpelmann model fits to nucleon electromagnetic form factors
journal, August 2001


The size of the proton
journal, July 2010

  • Pohl, Randolf; Antognini, Aldo; Nez, François
  • Nature, Vol. 466, Issue 7303
  • DOI: 10.1038/nature09250

The Coulomb Scattering of Relativistic Electrons by Nuclei
journal, December 1948


Nucleon and Roper electromagnetic elastic and transition form factors
journal, February 2012


Pion Distribution Amplitude from Lattice QCD
journal, August 2013


Scattering of Polarized Leptons at High Energy
journal, January 1969


Flavor Decomposition of the Elastic Nucleon Electromagnetic Form Factors
journal, June 2011


Coulomb distortion in high- Q 2 elastic e p scattering
journal, August 2004


Global analysis of proton elastic form factor data with two-photon exchange corrections
journal, September 2007


Flavor decomposition of the nucleon electromagnetic form factors
journal, December 2012


Aspects of hadron physics
journal, January 2007

  • Roberts, C. D.; Bhagwat, M. S.; Höll, A.
  • The European Physical Journal Special Topics, Vol. 140, Issue 1
  • DOI: 10.1140/epjst/e2007-00003-5

Measurement of proton and neutron electromagnetic form factors at squared four-momentum transfers up to 3 (GeV/c)2
journal, July 1973


Revealing Dressed Quarks via the Proton’s Charge Distribution
journal, September 2013


Extraction of two-photon contributions to the proton form factors
journal, January 2005


Final analysis of proton form factor ratio data at Q 2 = 4.0 , 4.8, and 5.6 GeV 2
journal, April 2012


Measurement of GEp/GMp via polarization transfer at Q2 = 0.4 GeV /c2
journal, September 2001

  • Pospischil, Th.; Bartsch, P.; Baumann, D.
  • The European Physical Journal A, Vol. 12, Issue 1
  • DOI: 10.1007/s100500170046

Model-independent properties of two-photon exchange in elastic electron-proton scattering
journal, November 2004


Parity-Violating Electron Scattering and the Electric and Magnetic Strange Form Factors of the Nucleon
journal, November 2012