D-state effects in the electromagnetic<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>N</mml:mi><mml:mi>Δ</mml:mi></mml:math>transition

Ramalho, G.; Peña, M. T.; Gross, Franz

doi:10.1103/physrevd.78.114017

Cited by 74 publications

(270 citation statements)

References 120 publications

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“…At this point we restrict the calculations to the region Q 2 ≤ 2 GeV 2 , since the main goal at the moment is the study of parametrizations consistent with the Siegert's theorem, near Q 2 = Q 2 P S ≃ −0.09 GeV 2 . For larger Q 2 there are discrepancies between the data from different groups [20,25], which are not relevant for the discussion near the pseudo-threshold. In Fig.…”

Section: B Improved Parametrizations Of Ge and Gcmentioning

confidence: 86%

“…Using the properties of Dirac and Rarita-Schwinger spinors, we can conclude that (ū 3 γ 5 u) = 2 3 |q| 2M ∝ |q| and (ū 3 u) = − 2 3 = O(1), near the pseudo-threshold [19,20]. Applying those results, one obtains S 1/2 = O(|q| 2 ) for ∆(1232) resonance and S 1/2 = O(|q|) for N (1520) resonance.…”

Section: B Scalar Amplitudementioning

confidence: 99%

“…The four form factors are not all independent, only three of them are independent. Using the current conservation condition, q · J = 0, we can conclude that [19,20] …”

Section: Notationmentioning

confidence: 99%

“…Instead of the elementary form factors G i , alternatively we can use the multipole form factors: magnetic dipole (G M ), electric quadrupole (G E ) and Coulomb quadrupole (G C ), defined as [12,19,20] …”

Section: Notationmentioning

confidence: 99%

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Improved empirical parametrizations of theγN→Δ(1232)andγN<

Ramalho

2016

Phys. Rev. D

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Section: B Improved Parametrizations Of Ge and Gcmentioning

confidence: 86%

Section: B Scalar Amplitudementioning

confidence: 99%

“…The four form factors are not all independent, only three of them are independent. Using the current conservation condition, q · J = 0, we can conclude that [19,20] …”

Section: Notationmentioning

confidence: 99%

Section: Notationmentioning

confidence: 99%

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Improved empirical parametrizations of theγN→Δ(1232)andγN<

Ramalho

2016

Phys. Rev. D

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“…Another covariant approach is the covariant spectator model of Ref. [541], which has been actively explored for a range of observables including various elastic and transition form factors of octet and decuplet baryons [542][543][544][545][546][547]; a recent overview can be found in Ref. [548].…”

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

418

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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Pion-Cloud Contribution to the $$N\rightarrow \varDelta $$ Transition Form Factors

Jung

Schweiger

2020

Recent Progress in Few-Body Physics

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We examine the contribution of the pion cloud to the electromagnetic N → ∆ transition form factors within a relativistic hybrid constituent-quark model. In this model baryons consist not only of the 3q valence component, but contain, in addition, a 3qπ non-valence component. We start with constituent quarks which are subject to a scalar, isoscalar confining force. This leads to an SU (6) spin-flavor symmetric spectrum with degenerate nucleon and Delta masses. Mass splitting is caused by pions which are assumed to couple directly to the quarks. The point-form of relativistic quantum mechanics is employed to achieve a relativistically invariant description of this system. The N → ∆ transition current is then determined from the one-photon exchange contribution to the ∆ electroproduction amplitude. We will give predictions for the ratios REM and RSM of electric to magnetic and Coulomb to magnetic form factors, which are supposed to be most sensitive to pion-cloud effects.

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D-state effects in the electromagneticNΔtransition

Cited by 74 publications

References 120 publications

Improved empirical parametrizations of theγN→Δ(1232)andγN<

Improved empirical parametrizations of theγN→Δ(1232)andγN<

Baryons as relativistic three-quark bound states

Pion-Cloud Contribution to the $$N\rightarrow \varDelta $$ Transition Form Factors

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D-state effects in the electromagneticNΔtransition

Cited by 74 publications

References 120 publications

Improved empirical parametrizations of theγ*N→Δ(1232)andγ*N<

Improved empirical parametrizations of theγ*N→Δ(1232)andγ*N<

Baryons as relativistic three-quark bound states

Pion-Cloud Contribution to the $$N\rightarrow \varDelta $$ Transition Form Factors

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Product

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Improved empirical parametrizations of theγN→Δ(1232)andγN<

Improved empirical parametrizations of theγN→Δ(1232)andγN<