Signatures of chiral dynamics in the Nucleon to Delta transition

Abstract

Utilizing the methods of chiral effective field theory we present an analysis of the electromagnetic $N\Delta$-transition current in the framework of the non-relativistic "small scale expansion" (SSE) to leading-one-loop order. We discuss the momentum dependence of the magnetic dipole, electric quadrupole and coulomb quadrupole transition form factors up to a momentum transfer of $Q^2<0.3$ GeV${}^2$. Particular emphasis is put on the identification of the role of chiral dynamics in this transition. Our analysis indicates that there is indeed non-trivial momentum dependence in the two quadrupole form factors at small $Q^2<0.15$ GeV${}^2$ arising from long distance pion physics, leading for example to negative radii in the (real part of the) quadrupole transition form factors. We compare our results with the EMR($Q^2$) and CMR($Q^2$) multipole-ratios from pion-electroproduction experiments and find a remarkable agreement up to four-momentum transfer of $Q^2\approx 0.3$ GeV${}^2$. Finally, we discuss the chiral extrapolation of the three transition form factors at $Q^2=0$, identifying rapid changes in the (real part of the) quark-mass dependence of the quadrupole transition moments for pion masses below 200 MeV, which arise again from long distance pion dynamics. Our findings indicate that dipole extrapolation methods currently used in lattice QCD analyses of baryon form factors are not applicable for the chiral extrapolation of $N\Delta$ quadrupole transition form factors.

arXiv comment24 pages, 19 figures

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Cited by in corpus (40)

• Electromagnetic excitation of the Delta(1232)-resonance
• Electromagnetic Excitation of Nucleon Resonances
• Nucleon isovector couplings from $N_f=2$ lattice QCD
• Axial coupling constant of the nucleon for two flavours of dynamical quarks in finite and infinite volume
• Predictive powers of chiral perturbation theory in Compton scattering off protons
• Axial Nucleon and Nucleon to Delta form fractors and the Goldberger-Treiman Relations from Lattice QCD
• Nucleon axial charge and pion decay constant from two-flavor lattice QCD
• D-state effects in the electromagnetic N-Delta transition
• A Covariant model for the nucleon and the $\Delta$
• Valence quark contribution for the gamma N -> Delta quadrupole transition extracted from lattice QCD
• The axial N to Delta transition form factors from Lattice QCD
• Nucleon to Delta electromagnetic transition in the Dyson-Schwinger approach
• Hadron structure at low Q^2
• Determination of quadrupole strengths in the gamma*p-->Delta(1232) transition at Q2= 0.20 (GeV/c)2
• A model for the Delta(1600) resonance and gamma N -> Delta(1600) transition
• Nucleon and gamma N -> Delta lattice form factors in a constituent quark model
• Magnetic moments of the spin-$\frac{3}{2}$ doubly heavy baryons
• Measurements of the gamma*p->Delta Reaction At Low Q^2: Probing the Mesonic Contribution
• Electromagnetic Transition Form Factors of Baryon Resonances
• Nucleon-to-Delta axial transition form factors in relativistic baryon chiral perturbation theory
• Electromagnetic form factors of the Delta in a S-wave approach
• Beam normal spin asymmetry for the $ep\to e\Delta (1232)$ process
• Chiral symmetry and the axial nucleon to Delta(1232) transition form factors
• Measurements of the γ* p --> Δ(1232) reaction at low Q2
• Electroexcitation of the ${\Delta }^{+}(1232)$ at low momentum transfer
• Baryon transition form factors at the pole
• New low-$Q^2$ measurements of the ${\gamma }^{\ast }N\to \Delta (1232)$ Coulomb quadrupole form factor, pion cloud parametrizations and Siegert's theorem
• Light-cone sum rules for the $N\gamma \Delta$ transitions for real photons
• Virtual Compton Scattering measurements in the nucleon resonance region
• The Delta(1232) Resonance in Chiral Effective Field Theory
• Nucleon-to-Delta transition form factors in chiral effective field theory using the complex-mass scheme
• Electromagnetic transition properties of $\Delta \to N\gamma$ in a hypercentral scheme
• Energy Dependence of the Delta Resonance: Chiral Dynamics in Action
• Q^2-evolution of nucleon-to-resonance transition form factors in a QCD-inspired vector-meson-dominance model
• 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
• Exclusive and semiexclusive production of ${\mu }^{+}{\mu }^{-}$ pairs with $\Delta$ isobars and other resonances in the final state and the size of absorption effects
• A dispersive approach to pion photo- and electroproduction
• Pion electroproduction measurements in the nucleon resonance region
• Chiral extrapolation of the doubly charmed baryons magnetic properties