scholarly journals Dispersion-theoretical analysis of the electromagnetic form factors of the nucleon: Past, present and future

2021 ◽  
Vol 57 (8) ◽  
Author(s):  
Yong-Hui Lin ◽  
Hans-Werner Hammer ◽  
Ulf-G. Meißner
Keyword(s):  
Theoretical Analysis ◽  
Bayesian Methods ◽  
Form Factors ◽  
Systematic Errors ◽  
Electromagnetic Form Factors ◽  
Detailed Calculation ◽  
Spectral Functions ◽  
Statistical Errors ◽  
Magnetic Form Factors

AbstractWe review the dispersion-theoretical analysis of the electromagnetic form factors of the nucleon. We emphasize in particular the role of unitarity and analyticity in the construction of the isoscalar and isovector spectral functions. We present new results on the extraction of the nucleon radii, the electric and magnetic form factors and the extraction of $$\omega $$ ω -meson couplings. All this is supplemented by a detailed calculation of the theoretical uncertainties, using bootstrap and Bayesian methods to pin down the statistical errors, while systematic errors are determined from variations of the spectral functions. We also discuss the physics of the time-like form factors and point out further issues to be addressed in this framework.

scholarly journals Nucleon Axial and Electromagnetic Form Factors

2018 ◽  
Vol 175 ◽  
pp. 06033 ◽  
Author(s):  
Yong-Chull Jang ◽  
Tanmoy Bhattacharya ◽  
Rajan Gupta ◽  
Huey-Wen Lin ◽  
Boram Yoon
Keyword(s):  
Excited States ◽  
Finite Volume ◽  
Magnetic Moment ◽  
Lattice Spacing ◽  
Form Factors ◽  
Electromagnetic Form Factors ◽  
Charge Radii ◽  
Model Independent ◽  
Magnetic Form Factors

We present results for the isovector axial, induced pseudoscalar, electric, and magnetic form factors of the nucleon. The calculations were done using 2 + 1 + 1-flavor HISQ ensembles generated by the MILC collaboration with lattice spacings a ≈ 0.12, 0.09, 0.06 fm and pion masses Mπ ≈ 310, 220, 130 MeV. Excited-states contamination is controlled by using four-state fits to two-point correlators and by comparing two-versus three-states in three-point correlators. The Q2 behavior is analyzed using the model independent z-expansion and the dipole ansatz. Final results for the charge radii and magnetic moment are obtained using a simultaneous fit in Mπ, lattice spacing a and finite volume.

The role of electromagnetic form factors in meson exchange currents

1988 ◽  
Vol 331 (4) ◽  
pp. 509-518 ◽  
Author(s):  
S. K. Singh ◽  
W. Leidemann ◽  
H. Arenh�vel
Keyword(s):  
Form Factors ◽  
Meson Exchange ◽  
Electromagnetic Form Factors ◽  
Meson Exchange Currents

scholarly journals Dispersion-theoretical analysis of the nucleon electromagnetic form factors

1996 ◽  
Vol 596 (3-4) ◽  
pp. 367-396 ◽  
Author(s):  
P. Mergell ◽  
Ulf-G. Meißner ◽  
D. Drechsel
Keyword(s):  
Theoretical Analysis ◽  
Form Factors ◽  
Electromagnetic Form Factors

scholarly journals VIOLATIONS OF LORENTZ COVARIANCE IN LIGHT FRONT QUARK MODELS

2000 ◽  
Vol 15 (36) ◽  
pp. 2191-2204 ◽  
Author(s):  
K. BODOOR ◽  
H. J. WEBER ◽  
T. FREDERICO ◽  
M. BEYER
Keyword(s):  
Rotational Symmetry ◽  
Form Factors ◽  
Electromagnetic Form Factors ◽  
Thomas Model ◽  
Triangle Diagram ◽  
Charge Form ◽  
Null Plane ◽  
Plane Projection ◽  
Magnetic Form Factors ◽  
Quark Models

Electromagnetic form factors of the nucleon from relativistic quark models are analyzed: Results from null-plane projection of the Feynman triangle diagram are compared with a Bakamjian–Thomas model. The magnetic form factors of the models differ by about 15% at spacelike momentum transfer 0.5 GeV2, while the charge form factors are much closer. Spurious contributions to electromagnetic form factors due to violations of rotational symmetry are eliminated for both models. One method changes magnetic form factors by about 10%, whereas the charge form factors remain nearly the same. Another one changes the charge form factor of the Bakamjian–Thomas model by more than 50%.

scholarly journals Role of mesons in the electromagnetic form factors of the nucleon

2010 ◽  
Vol 82 (4) ◽  
Author(s):  
C. Crawford ◽  
T. Akdogan ◽  
R. Alarcon ◽  
W. Bertozzi ◽  
E. Booth ◽  
...  
Keyword(s):  
Form Factors ◽  
Electromagnetic Form Factors
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