Electromagnetic Properties of the Delta(1232)

Abstract

We calculate the electromagnetic moments and radii of the Delta(1232) in the nonrelativistic quark model, including two-body exchange currents. We show that two-body exchange currents lead to nonvanishing Delta and N-->Delta transition quadrupole moments even if the wave functions have no D-state admixture. The usual explanation based on the single-quark transition model involves D-state admixtures but no exchange currents. We derive a parameter- free relation between the N-->Delta transition quadrupole moment and the neutron charge radius: Q(N-->Delta) = r^2(neutron)/sqrt(2). Furthermore, we calculate the M1 and E2 amplitudes for the process photon + N -->Delta. We find that the E2 amplitude receives sizeable contributions from exchange currents. These are more important than the ones which result from D-state admixtures due to tensor forces between quarks if a reasonable quark core radius of about 0.6 fm is used. We obtain a ratio of E2/M1=-3.5%.

32 pages, LaTeX, 6 Postscript figures, to appear in Physical Review C

References in corpus (7)

• The Spectrum of the Nucleons and the Strange Hyperons and Chiral Dynamics
• Baryons as non-topological chiral solitons
• Decuplet Baryon Structure from Lattice QCD
• The position and the residues of the delta resonance pole in pion photoproduction
• Radiative Decays of Hyperons in the Skyrme Model: E2/M1 Transitions
• Magnetic Moments of the Octet Baryons in a Chiral Quark Potential Model
• Unitary ambiguity in the extraction of the E2/M1 ratio for the $\gamma N\leftrightarrow \Delta$ transition

Cited by in corpus (86)

• Electromagnetic excitation of the Delta(1232)-resonance
• Electroexcitation of nucleon resonances
• Weak Pion Production off the Nucleon
• Dynamical Study of the Delta Excitation in N(e,e' pi) Reactions
• Study of Non-Strange Baryon Resonances with Meson Photoproduction
• Nucleon Charge and Magnetization Densities from Sachs Form Factors
• Multipole analysis of pion photoproduction based on fixed t dispersion relations and unitarity
• Determination of the E2/M1 Ratio in the γN \to Δ(1232) Transition from a Simultaneous Measurement of p(\vecγ,p)π^0 and p(\vecγ,π^+)n
• Search for Quadrupole Strength in the Electro-excitation of the Delta(1232)
• Nucleon and $\Delta$ elastic and transition form factors
• Intrinsic quadrupole moment of the nucleon
• Electromagnetic structure of the lowest-lying decuplet resonances in covariant chiral perturbation theory
• D-state effects in the electromagnetic N-Delta transition
• Quadrupole Moments of N and Delta in the 1/N_c Expansion
• Elastic and transition form factors of the Δ(1232)
• Electric quadrupole and magnetic octupole moments of the Delta
• Quadrupole moments of baryons
• Magnetic moments of the SU(3) decuplet baryons in the chiral quark-soliton model
• Valence quark contribution for the gamma N -> Delta quadrupole transition extracted from lattice QCD
• Delta and Omega electromagnetic form factors in a Dyson-Schwinger/Bethe-Salpeter approach
• Electromagnetic N->Delta transition and neutron form factors
• Electromagnetic form factors of the Delta with D-waves
• Light Cone Sum Rules for gamma* N -> Delta Transition Form Factors
• Large N_c, Constituent Quarks, and N, Delta Charge Radii
• Charged current weak electroproduction of Delta resonance
• ${\Omega }_c\gamma \to {\Omega }_c^{\ast }$ transition in lattice QCD
• Delta-baryon mass in a covariant Faddeev approach
• The d'-dibaryon in a colored cluster model
• Electromagnetic Transition Form Factors of Baryon Resonances
• Electromagnetic properties of the Delta(1232) and decuplet baryons in the self-consistent SU(3) chiral quark-soliton model
• Deviation of the Nucleon Shape From Spherical Symmetry: Experimental Status
• Light flavor baryon spectrum with higher order hyperfine interactions
• Axial $N\to \Delta (1232)$ and $N\to N^{\star }(1440)$ transition form factors
• Baryon octupole moments
• Magnetic moments of $J^P={\frac{3}{2}}^{+}$ decuplet baryons using effective quark masses in chiral constituent quark model
• Properties of Nucleon Resonances by means of a Genetic Algorithm
• Moments of the neutron charge form factor and the N->Delta quadrupole transition
• Electromagnetic form factors of the Delta in a S-wave approach
• Radiative decays of decuplet hyperons
• Electromagnetic nucleon-delta transition in the perturbative chiral quark model
• Axial-vector form factors for the low lying octet baryons in the chiral quark constituent model
• Quadrupole moments of low lying baryons with spin 1/2^+, spin 3/2^+, and spin 3/2^+ \to 1/2^+ transitions
• The electroproduction of the $\Delta$(1232) in the chiral quark-soliton model
• Exchange Currents in Photoproduction of Baryon Resonances
• Delta-to-N-gamma Coulomb Quadrupole Amplitude in PQCD
• Parametrizations of the ${\gamma }^{\ast }N\to \Delta (1232)$ quadrupole form factors and Siegert's theorem
• Improved empirical parametrizations of the ${\gamma }^{\ast }N\to \Delta (1232)$ and ${\gamma }^{\ast }N\to N(1520)$ helicity amplitudes and the Siegert's theorem
• Axial exchange currents and nucleon spin
• Problems with Extraction of the Nucleon to Delta(1232) Photonic Amplitudes
• Magnetic dipole moment of the $\Delta (1232)$ in chiral perturbation theory
• Hints on the quadrupole deformation of the $\Delta$(1232)
• Lattice QCD study of the elastic and transition form factors of charmed baryons
• On the extraction of electromagnetic properties of the Delta(1232) excitation from pion photoproduction
• New low-$Q^2$ measurements of the ${\gamma }^{\ast }N\to \Delta (1232)$ Coulomb quadrupole form factor, pion cloud parametrizations and Siegert's theorem
• Exchange currents in octet hyperon charge radii
• Two-photon-exchange effects in the electro-excitation of the $\Delta$ resonance
• The Matter and the Pseudoscalar Densities in Lattice QCD
• Nucleon-to-Delta transition form factors in chiral effective field theory using the complex-mass scheme
• Transition magnetic moments of $J^P={\frac{3}{2}}^{+}$ decuplet to $J^P={\frac{1}{2}}^{+}$ octet baryons in the chiral constituent quark model
• Dirac form factors and electric charge radii of baryons in the combined chiral and 1/N_c expansions
• $\Delta$(1232) electroproduction amplitudes in chiral soliton models of the nucleon
• Low-$Q^2$ empirical parametrizations of the $N^{\ast }$ helicity amplitudes
• Electromagnetic transition form factors, $E2/M1$ and $C2/M1$ ratios of the baryon decuplet
• Nucleon deformation and atomic spectroscopy
• Non-spherical proton shape and hydrogen hyperfine splitting
• Analysis of the quadrupole deformation of $\Delta$(1232) within an effective Lagrangian model for pion photoproduction from the nucleon
• Electromagnetic multipole moments of baryons
• Magnetic moments and electromagnetic radii of nucleon and $\Delta (1232)$ in an extended GBE model
• Combined parametrization of the neutron electric form factor and the ${\gamma }^{\ast }N\to \Delta (1232)$ quadrupole form factors
• A relation between the charge radii of π^{+},\K^{+},K^{o} derived by the general QCD parametrization
• Stability of the E2/M1 ratio at the T-matrix pole
• Decays, contact P-wave interactions and hyperfine structure in Omega- exotic atoms
• Current conservation, screening and the magnetic moment of the $\Delta$ resonance: 2. Formulation with quark degrees of freedom 3. Magnetic moment of the ${\Delta }^o$ and ${\Delta }^{-}$ resonances
• Axial-vector charges of the spin ${\frac{1}{2}}^{+}$ and spin ${\frac{3}{2}}^{+}$ light and charmed baryons in the SU(4) chiral quark constituent model
• Photo-production of Nucleon Resonances and Nucleon Spin Structure Function in the Resonance Region
• Static and dynamic properties of hadronic systems with heavy quarks b and c
• Extended van Royen-Weisskopf formalism for lepton-antilepton meson decay widths within non-relativistic quark models
• Effects of Finite Size of Constituent Quarks on Nucleon-Nucleon Interaction
• Nucleon magnetic moments in an extended chiral constituent quark model
• Meson exchange and nucleon polarizabilities in the quark model
• The pion photoproduction in the Δ(1232) region
• Electromagnetic Form Factors of the Nucleon in a Relativistic Quark Pair Creation Model
• Probing Delta structure with pion electromagnetic production
• Electromagnetic polarizabilities of the spin-$\frac{3}{2}$ baryons in heavy baryon chiral perturbation theory
• Current conservation, screening and the magnetic moment of the $\Delta$ resonance. -- 1. Formulation without quark degrees of freedom
• Excited nucleon electromagnetic form factors from broken spin-flavor symmetry