Nucleon to Delta electromagnetic transition in the Dyson-Schwinger approach

Abstract

We study the N-Delta-gamma transition in the Dyson-Schwinger approach. The nucleon and Delta baryons are treated as quark-diquark bound states, where the ingredients of the electromagnetic transition current are computed self-consistently from the underlying dynamics in QCD. Although our approach does not include pion-cloud effects, we find that the electric and Coulomb quadrupole form-factor ratios R_EM and R_SM show good agreement with experimental data. This implies that the deformation from a spherical charge distribution inside both baryons can be traced back to the appearance of p waves in the nucleon and Delta bound-state amplitudes which are a consequence of Poincare covariance. On the other hand, the dominant transition amplitude, i.e. the magnetic dipole transition form factor, underestimates the data by ~25% in the static limit whereas agreement is achieved at larger momentum transfer, which is consistent with missing pion-cloud contributions. We furthermore find that the static properties of the form factors are not very sensitive to a variation of the current-quark mass.

21 pages, 9 figures, 4 tables. Added references

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Cited by in corpus (35)

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• Explanation and Prediction of Observables using Continuum Strong QCD
• Nucleon and $\Delta$ elastic and transition form factors
• New Results from the Studies of the $N(1440)1/2^{+}$, $N(1520)3/2^{-}$, and $\Delta (1620)1/2^{-}$ Resonances in Exclusive $ep\to e^{\prime }{p}^{\prime }{\pi }^{+}{\pi }^{-}$ Electroproduction with the CLAS Detector
• Baryon effects on the location of QCD's critical end point
• Three Lectures on Hadron Physics
• Elastic and transition form factors of the Δ(1232)
• Recent developments in bound-state calculations using the Dyson-Schwinger and Bethe-Salpeter equations
• Understanding the nucleon as a Borromean bound-state
• Insights into the gamma* N -> Delta transition
• Nucleon elastic form factors at accessible large spacelike momenta
• Dissecting nucleon transition electromagnetic form factors
• Nucleon Compton scattering in the Dyson-Schwinger approach
• Rôle of the pion electromagnetic form factor in the $\Delta (1232)\to {\gamma }^{\ast }N$ timelike transition
• Transition form factors: ${\gamma }^{\ast }+p\to \Delta (1232)$, $\Delta (1600)$
• Studies of N^* structure from the CLAS meson electroproduction data
• Valence quark and meson cloud contributions to the ${\gamma }^{\ast }N\to N^{\ast }(1520)$ form factors
• Excited hadrons and the analytical structure of bound-state interaction kernels
• Nucleon resonances in Compton scattering
• Electromagnetic transition form factors of baryons in the space-like momentum region
• On the effect of resonances in the quark-photon vertex
• More about the light baryon spectrum
• Hyperon elastic electromagnetic form factors in the space-like momentum region
• Composition of low-lying $\mathbf{J}={\frac{3}{2}}^{\pm }\mathbf{\Delta }$-baryons
• New low-$Q^2$ measurements of the ${\gamma }^{\ast }N\to \Delta (1232)$ Coulomb quadrupole form factor, pion cloud parametrizations and Siegert's theorem
• Progress in the calculation of nucleon transition form factors
• Electromagnetic transition form factors, $E2/M1$ and $C2/M1$ ratios of the baryon decuplet
• Global Data-Driven Determination of Baryon Transition Form Factors
• Combined parametrization of the neutron electric form factor and the ${\gamma }^{\ast }N\to \Delta (1232)$ quadrupole form factors
• Space-like Electromagnetic Form Factors of Lambda- and Sigma-Baryons from Quark-Diquark Faddeev Equations
• Electromagnetic baryon form factors in the Poincare-covariant Faddeev approach
• ${\gamma }_{\mathbf{v}}\mathbf{N}{\mathbf{N}}^{\ast }$ Electrocouplings in Dyson-Schwinger Equations
• Elastic and Transition Form Factors in DSEs
• Nucleon-to-Resonance Form Factors at Large Photon Virtualities
• Valence-quark structure N* resonances from DSEs