Electroexcitation of nucleon resonances

Aznauryan, I.G.; Burkert, V. D.

doi:10.1016/j.ppnp.2011.08.001

Cited by 234 publications

(392 citation statements)

References 227 publications

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“…A big step forward has been made at Jefferson Lab in the last decade where precise data over a large Q 2 range have been collected in pion electroproduction experiments. The interpretation of the electroproduction data and helicity amplitudes using different analyses is reviewed in [11,12]. Currently, both photo-and electroproduction of mesons off nucleons constitute the main experimental approaches for the discovery of new nucleon resonances and our understanding of electromagnetic baryon structure in the spacelike momentum region.…”

Section: Nucleon Resonancesmentioning

confidence: 99%

“…Currently, both photo-and electroproduction of mesons off nucleons constitute the main experimental approaches for the discovery of new nucleon resonances and our understanding of electromagnetic baryon structure in the spacelike momentum region. In the following we will give a very brief survey of the most prominent resonances and their basic properties; more details can be found in the dedicated reviews [4,[10][11][12][13][14].…”

Section: Nucleon Resonancesmentioning

confidence: 99%

“…The multipole amplitudes are linear combinations of the transverse partial wave helicity amplitudes, which at the resonance locations are related to the N γ * → N * helicity amplitudes (see e.g. [11,13,30] for the explicit formulas).…”

Section: (24)mentioning

confidence: 99%

“…In the following we will sketch the basic ideas behind these approaches and refer to Refs. [4,11,13,55,56] for details and a comprehensive list of references. The common goal is to calculate the T-matrix or, equivalently, its multipole expansion in terms of interaction potentials V ij , which are split into a non-resonant background and resonant contributions.…”

Section: Helicity Amplitudes Vs Transition Form Factorsmentioning

confidence: 99%

“…An approximative way to include rescattering effects is the K-matrix formulation of (2.21), which has found widespread applications and reduces the integral equations to a set of algebraic relations. For example, the unitary isobar models employed by MAID [12,30,57] and the JLab group [11,58] separate the electroproduction amplitude into a background and a resonant part, 22) where the former is expressed through the K-matrix which is subsequently approximated by the background potential V B γπ . The resonant contributions are parametrized by a Breit-Wigner form including the resonance masses m R and the total decay width Γ, where the coefficients c R include the transition form factors and their fit parameters.…”

Section: Helicity Amplitudes Vs Transition Form Factorsmentioning

confidence: 99%

See 4 more Smart Citations

Baryons as relativistic three-quark bound states

Eichmann

Sanchis-Alepuz

Williams

et al. 2016

Progress in Particle and Nuclear Physics

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503

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We review the spectrum and electromagnetic properties of baryons described as relativistic three-quark bound states within QCD. The composite nature of baryons results in a rich excitation spectrum, whilst leading to highly non-trivial structural properties explored by the coupling to external (electromagnetic and other) currents. Both present many unsolved problems despite decades of experimental and theoretical research. We discuss the progress in these fields from a theoretical perspective, focusing on nonperturbative QCD as encoded in the functional approach via Dyson-Schwinger and Bethe-Salpeter equations. We give a systematic overview as to how results are obtained in this framework and explain technical connections to lattice QCD. We also discuss the mutual relations to the quark model, which still serves as a reference to distinguish 'expected' from 'unexpected' physics. We confront recent results on the spectrum of non-strange and strange baryons, their form factors and the issues of two-photon processes and Compton scattering determined in the DysonSchwinger framework with those of lattice QCD and the available experimental data. The general aim is to identify the underlying physical mechanisms behind the plethora of observable phenomena in terms of the underlying quark and gluon degrees of freedom.

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Section: Nucleon Resonancesmentioning

confidence: 99%

Section: Nucleon Resonancesmentioning

confidence: 99%

Section: (24)mentioning

confidence: 99%

Section: Helicity Amplitudes Vs Transition Form Factorsmentioning

confidence: 99%

Section: Helicity Amplitudes Vs Transition Form Factorsmentioning

confidence: 99%

See 3 more Smart Citations

Baryons as relativistic three-quark bound states

Eichmann

Sanchis-Alepuz

Williams

et al. 2016

Progress in Particle and Nuclear Physics

402

503

View full text Add to dashboard Cite

show abstract

Untitled

Segovia¹

2017

Light Cone 2015

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A symmetry preserving framework for the study of continuum Quantum Chromodynamics (QCD) is obtained from a truncated solution of the QCD equations of motion or QCD's DysonSchwinger equations (DSEs). A nonperturbative solution of the DSEs enables the study of, e.g., hadrons as composites of dressed-quarks and dressed-gluons, the phenomena of confinement and dynamical chiral symmetry breaking (DCSB), and therefrom an articulation of any connection between them. It is within this context that we present a unified study of Nucleon, Delta and Roper elastic and transition form factors, and compare predictions made using a framework built upon a Faddeev equation kernel and interaction vertices that possess QCD-like momentum dependence with results obtained using a symmetry-preserving treatment of a vector ⊗ vector contact-interaction.

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Elastic and Transition Form Factors of the Δ(1232)

et al. 2013

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Predictions obtained with a confining, symmetry-preserving treatment of a vector ⊗ vector contact interaction at leading-order in a widely used truncation of QCD's Dyson-Schwinger equations are presented for ∆ and Ω baryon elastic form factors and the γN → ∆ transition form factors. This simple framework produces results that are practically indistinguishable from the best otherwise available, an outcome which highlights that the key to describing many features of baryons and unifying them with the properties of mesons is a veracious expression of dynamical chiral symmetry breaking in the hadron bound-state problem. The following specific results are of particular interest. The ∆ elastic form factors are very sensitive to m ∆ . Hence, given that the parameters which define extant simulations of lattice-regularised QCD produce ∆-resonance masses that are very large, the form factors obtained therewith are a poor guide to properties of the ∆(1232). Considering the ∆-baryon's quadrupole moment, whilst all computations produce a negative value, the conflict between theoretical predictions entails that it is currently impossible to reach a sound conclusion on the nature of the ∆-baryon's deformation in the infinite momentum frame. Results for analogous properties of the Ω baryon are less contentious. In connection with the N → ∆ transition, the Ash-convention magnetic transition form factor falls faster than the neutron's magnetic form factor and nonzero values for the associated quadrupole ratios reveal the impact of quark orbital angular momentum within the nucleon and ∆; and, furthermore, these quadrupole ratios do slowly approach their anticipated asymptotic limits.

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Electroexcitation of nucleon resonances

Cited by 234 publications

References 227 publications

Baryons as relativistic three-quark bound states

Baryons as relativistic three-quark bound states

Untitled

Elastic and Transition Form Factors of the Δ(1232)

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