Q^2-evolution of nucleon-to-resonance transition form factors in a QCD-inspired vector-meson-dominance model

Abstract

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 NRγ-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-Δ(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-Δ(1232) form factors.

arXiv comment22 pages, 22 PS figures, REVTeX 4; v2: +3 refs, minor editorial changes

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Cited by in corpus (10)

• D-state effects in the electromagnetic N-Delta transition
• Nucleon to Delta electromagnetic transition in the Dyson-Schwinger approach
• Electromagnetic Transition Form Factors of Baryon Resonances
• Electromagnetic transition form factors of the Roper resonance in effective field theory
• Quark--hadron duality in lepton scattering off nuclei
• Single pion production in electron-proton interactions
• Gauge- and point-invariant vertices of nucleon-to-resonance interactions
• Low-Q^2 scaling behavior of the form-factor ratios for the NΔ(1232)-transition
• Symmetries of higher-spin fields and the electromagnetic N-N(1680) form factors
• Single Pion Production off Free Nucleons: Analysis of Photon, Electron, Pion and Neutrino Induced Processes