Nucleon electromagnetic form factors

We extend the formalism relating electromagnetic form factors to transverse quark charge densities in the light-front frame to the case of a spin-3/2 baryon and calculate these transverse densities for the ∆(1232) isobar using lattice QCD. The transverse charge densities for a transversely polarized spin-3/2 particle are characterized by monopole, dipole, quadrupole, and octupole patterns representing the structure beyond that of a pure point-like spin-3/2 particle. We present lattice QCD results for the ∆-isobar electromagnetic form factors for pion masses down to approximatively 350 MeV for three cases: quenched QCD, two-degenerate flavors of dynamical Wilson quarks, and three flavors of quarks using a mixed action that combines domain wall valence quarks and dynamical staggered sea quarks. We extract transverse quark charge densities from these lattice results and find that the ∆ is prolately deformed, as indicated by the fact that the quadrupole moment G E2 (0) is larger than the value −3 characterizing a point particle and the fact that the transverse charge density in a ∆ + of maximal transverse spin projection is elongated along the axis of the spin.

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“…Wilson fermions V # confs κ mπ mπ/mρ mN m∆ (GeV) (GeV) (GeV) SIM-I : Quenched, β = 6.0, a −1 = 2.14(6) GeV 32 3 …”

Section: Correlation Functionsmentioning

confidence: 99%

Quark transverse charge densities in the from lattice QCD

et al. 2009

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“…The combination of a high pressure (10 atm), highly polarized (50%) 3 He target and a large acceptance, open geometry spectrometer, BigBite, provides a better combination of statistical and systematic uncertainty than previous double-polarized G n E experiments [5]. BigBite is a non-focusing dipole magnet with an acceptance of 76 msr over a 40 cm target.…”

Section: Experimental Overviewmentioning

confidence: 99%

“…As the fourmomentum increases, the frame begins to move at relativistic speeds with respect to the lab frame, which affects the kinematics and interpretation of the structure [5].…”

Section: Physical Interpretation and The Breit Framementioning

confidence: 99%

“…As a result of this experiment and many others [5], as well as the Feshbach-Lomon wave function [22], a fit was performed. The result was the well-known Galster parametrization:…”

Section: Fig 23mentioning

confidence: 99%

“…For the neutron, the overall electrical neutrality means that the electric form factor is very small. Early experimental measurements were unable to distinguish between G n E = 0 and the Galster parametrization [5].…”

Section: Fig 23mentioning

confidence: 99%

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A Measurement of the neutron electric form factor at very large momentum transfer using polaried electrions scattering from a polarized helium-3 target

Kelleher

2010

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Knowledge of the electric and magnetic elastic form factors of the nucleon is essential for an understanding of nucleon structure. Of the form factors, the electric form factor of the neutron has been measured over the smallest range in Q 2 and with the lowest precision. Jefferson Lab experiment 02-013 used a novel new polarized 3 He target to nearly double the range of momentum transfer in which the neutron form factor has been studied and to measure it with much higher precision. Polarized electrons were scattered off this target, and both the scattered electron and neutron were detected. G n E was measured to be 0.0242 ± 0.0020(stat) ± 0.0061(sys) and 0.0247 ± 0.0029(stat) ± 0.0031(sys) at Q 2 = 1.7 and 2.5 GeV 2 , respectively.

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Asymmetric Backward Peaking Radiation Pattern from a Relativistic Particle Accelerated by Lightning Leader Tip Electric Field

Yücemöz

Füllekrug

2021

Preprint

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Nucleon electromagnetic form factors

Cited by 470 publications

References 275 publications

Quark transverse charge densities in the from lattice QCD

Quark transverse charge densities in the from lattice QCD

A Measurement of the neutron electric form factor at very large momentum transfer using polaried electrions scattering from a polarized helium-3 target

Asymmetric Backward Peaking Radiation Pattern from a Relativistic Particle Accelerated by Lightning Leader Tip Electric Field

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