The role of the pion cloud in electroproduction of the Δ(1232)

Fiolhais, M.; Golli, B.; Širca, S.

doi:10.1016/0370-2693(96)00130-x

Cited by 51 publications

(75 citation statements)

References 35 publications

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“…The dashed curves correspond to fit F1 with one-parameter logarithmic renormalization (39), the solid curves to fit F2 with two-parameter renormalization (40). The data points are denoted as follows:…”

Section: Quark-hadron Duality and High-q 2 Form-factor Behaviormentioning

confidence: 99%

“…Some of the most prominent approaches are: quark shell models such as chiral bag model [33] and numerous constituent quark models (single quark transition model [34], hypercentral model [35], model with two-body exchange currents [36] and so forth); soliton models (Skyrmion models [37,38], linear σ-model [39,40,41], chiral chromodielectric model [40,41], chiral quark-soliton model [42]); algebraic approach [43]; generalized parton distributions (see reviews [28,44,45,46,47]); chiral effective field theories [48,49]. The majority of these models are in quantitative agreement with the experimental data points just at small Q 2 < 1.5 GeV 2 .…”

Section: Introductionmentioning

confidence: 99%

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Q2-evolution of nucleon-to-resonance transition form factors in a QCD-inspired vector-meson-dominance model

Vereshkov

Volchanskiy

2007

Phys. Rev. D

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We adopt the vector-meson-dominance approach to investigate Q 2 -evolution of N R-transition form factors (N denotes nucleon and R an excited resonance) in the first and second resonance regions. The developed model is based upon conventional γN R-interaction Lagrangians, introducing three form factors for spin-3/2 resonances and two form factors for spin-1/2 nucleon excitations. Lagrangian form factors are expressed as dispersionlike expansions with four or five poles corresponding to the lowest excitations of the mesons ρ(770) and ω(782). Correct high-Q 2 form factor behavior predicted by perturbative QCD is due to phenomenological logarithmic renormalization of electromagnetic coupling constants and linear superconvergence relations between the parameters of the meson spectrum. The model is found to be in good agreement with all the experimental data on Q 2 -dependence of the transitions N ∆(1232), N N (1440), N N (1520), N N (1535). We present fit results and model predictions for high-energy experiments proposed by JLab. Besides, we make special emphasis on the transition to perturbative domain of N ∆(1232) form factors.

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Section: Quark-hadron Duality and High-q 2 Form-factor Behaviormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Q2-evolution of nucleon-to-resonance transition form factors in a QCD-inspired vector-meson-dominance model

Vereshkov

Volchanskiy

2007

Phys. Rev. D

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“…The electroexcitation amplitudes for the ∆ resonance have been analyzed in the framework of chiral quark models 3,11,12 . They are dominated by the M1 transition but contain also rather sizable quadrupole contributions E2 and C2.…”

Section: Emi2001: Submitted To World Scientific On March 29 2018mentioning

confidence: 99%

“…The CDM has been used as a model for the nucleon 1 in different approximations. Using the hedgehog coherent state approach supplemented by an angular momentum and isospin projection, several nucleon properties and of the nucleon-delta electromagnetic excitation have been obtained 1,2,3 . In the present work we concentrate on the description of the Roper resonance.…”

Section: Introductionmentioning

confidence: 99%

Roper Electroproduction Amplitudes in a Chiral Confinement Model

Fiolhais¹,

Alberto²,

Marques³

et al. 2002

Electromagnetic Interactions in Nuclear and Hadron Physics

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A description of the Roper using the chiral chromodielectric model is presented and the transverse A 1/2 and the scalar S 1/2 helicity amplitudes for the electromagnetic Nucleon-Roper transition are obtained for small and moderate Q 2 . The sign of the amplitudes is correct but the model predictions underestimate the data at the photon point. Our results do not indicate a change of sign in any amplitudes up to Q 2 ∼ 1 GeV 2 . The contribution of the scalar meson excitations to the Roper electroproduction is taken into account but it turns out to be small in comparison with the quark contribution. However, it is argued that mesonic excitations may play a more prominent role in higher excited states.

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“…The present work was partly motivated by the experience gained in the phenomenological description of the quadrupole electro-excitation of the ∆ within the linear σ-model (LSM) and the Chromo-Dielectric Model (CDM) in which the pionic degree of freedom was shown to play a dominant role [1]. In these models, the pion cloud practically saturates the electric and Coulomb quadrupole transition strengths and qualitatively reproduces the Q 2 -behaviour of the amplitudes.…”

Section: Introductionmentioning

confidence: 99%