Elastic and Transition Form Factors of the Δ(1232)

Segovia, Jorge; Chen, Ch.; Cloët, Ian C.; Roberts, Craig D.; Schmidt, S.; Wan, Shaolong

doi:10.1007/s00601-013-0734-x

Cited by 59 publications

(79 citation statements)

References 141 publications

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“…Closely related is the contactinteraction model developed in Refs. [344,509] which requires some modifications to the kernels to make it applicable to excited states; it has since been applied to nucleon, ∆ and Roper elastic and transition form factors [510][511][512]. A compilation of results together with a comparison with the quark-diquark model using momentum-dependent ingredients can be found in [506].…”

Section: B Kinematics Andmentioning

confidence: 99%

Baryons as relativistic three-quark bound states

Eichmann

Sanchis-Alepuz

Williams

et al. 2016

Progress in Particle and Nuclear Physics

421

530

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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: B Kinematics Andmentioning

confidence: 99%

Baryons as relativistic three-quark bound states

Eichmann

Sanchis-Alepuz

Williams

et al. 2016

Progress in Particle and Nuclear Physics

421

530

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“…It follows that, employed judiciously, a symmetry-preserving treatment of a vector × vector contact interaction can provide insights and useful results for those hadron observables whose measurement involves probe momenta less-than m g [6,7,[28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43]. Hadron masses are such quantities.…”

Section: Bound-state Equationsmentioning

confidence: 99%

Parity partners in the baryon resonance spectrum

Chen

Roberts

et al. 2017

Phys. Rev. C

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We describe a calculation of the spectrum of flavour-SU (3) octet and decuplet baryons, their parity partners, and the radial excitations of these systems, made using a symmetry-preserving treatment of a vector × vector contact interaction as the foundation for the relevant few-body equations. Dynamical chiral symmetry breaking generates nonpointlike diquarks within these baryons and hence, using the contact interaction, flavour-antitriplet scalar, pseudoscalar and vector, and flavour-sextet axial-vector quark-quark correlations can all play an active role. The model yields reasonable masses for all systems studied, and Faddeev amplitudes for ground states and associated parity partners that sketch a realistic picture of their internal structure: ground-state, even parity baryons are constituted, almost exclusively, from like-parity diquark correlations; but orbital angular momentum plays an important role in the rest-frame wave functions of odd-parity baryons, whose Faddeev amplitudes are dominated by odd-parity diquarks.

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“…[7] and results obtained using a confining, symmetry-preserving treatment of a vector ⊗ vector contact interaction in a widely-used leading-order (rainbow-ladder) truncation of QCD's Dyson-Schwinger equations (DSEs) [11][12][13]. This is a pertinent comparison because the contact-interaction (CI) framework has judiciously been applied to a large body of hadron phenomena [3,[14][15][16][17][18][19][20][21][22] and by contrasting the results obtained for the same observables one can expose those quantities which are most sensitive to the momentum dependence of elementary quantities in QCD. Of particular relevance herein is a comparison with Refs.…”

Section: Introductionmentioning

confidence: 99%

“…Of particular relevance herein is a comparison with Refs. [18,21,22], which together provide a complete body of CI results for the quantities we study. Those analyses explain that the CI framework produces hard form factors, curtails some quark orbital angular momentum correlations within a baryon, and suppresses two-loop diagrams in the elastic and transition electromagnetic currents, defects that are rectified in our QCD-based approach.…”

Section: Introductionmentioning

confidence: 99%

Nucleon and $${\Delta}$$ Δ Elastic and Transition Form Factors

et al. 2014

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We present a unified study of nucleon and ∆ 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. The comparison emphasises that experiments are sensitive to the momentum dependence of the running couplings and masses in the strong interaction sector of the Standard Model and highlights that the key to describing hadron properties is a veracious expression of dynamical chiral symmetry breaking in the bound-state problem. Amongst the results we describe, the following are of particular interest:possesses a zero at Q 2 = 9.5 GeV 2 ; any change in the interaction which shifts a zero in the proton ratio to larger Q 2 relocates a zero inthere is likely a value of momentum transfer above which G n E > G p E ; and the presence of strong diquark correlations within the nucleon is sufficient to understand empirical extractions of the flavour-separated form factors. Regarding the ∆(1232)-baryon, we find that, inter alia: the electric monopole form factor exhibits a zero; the electric quadrupole form factor is negative, large in magnitude, and sensitive to the nature and strength of correlations in the ∆(1232) Faddeev amplitude; and the magnetic octupole form factor is negative so long as rest-frame P -and D-wave correlations are included. In connection with the N → ∆ transition, the momentum-dependence of the magnetic transition form factor, G * M , matches that of G n M once the momentum transfer is high enough to pierce the meson-cloud; and the electric quadrupole ratio is a keen measure of diquark and orbital angular momentum correlations, the zero in which is obscured by meson-cloud effects on the domain currently accessible to experiment. Importantly, within each framework, identical propagators and vertices are sufficient to describe all properties discussed herein. Our analysis and predictions should therefore serve as motivation for measurement of elastic and transition form factors involving the nucleon and its resonances at high photon virtualities using modern electron-beam facilities.

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Elastic and Transition Form Factors of the Δ(1232)

Cited by 59 publications

References 141 publications

Baryons as relativistic three-quark bound states

Baryons as relativistic three-quark bound states

Parity partners in the baryon resonance spectrum

Nucleon and $${\Delta}$$ Δ Elastic and Transition Form Factors

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