Hints on the quadrupole deformation of the $\Delta$(1232)

Abstract

The E2/M1 ratio (EMR) of the $\Delta$(1232) is extracted from the world data in pion photoproduction by means of an Effective Lagrangian Approach (ELA).This quantity has been derived within a crossing symmetric, gauge invariant, and chiral symmetric Lagrangian model which also contains a consistent modern treatment of the $\Delta$(1232) resonance. The \textit{bare} s-channel $\Delta$(1232) contribution is well isolated and Final State Interactions (FSI) are effectively taken into account fulfilling Watson's theorem. The obtained EMR value, EMR$=(-1.30\pm 0.52)$%, is in good agreement with the latest lattice QCD calculations [Phys. Rev. Lett. 94, 021601 (2005)] and disagrees with results of current quark model calculations.

Enlarged conclusions and explanations on the E2/M1 ratio. Figure 3 improved. References updated. 5 pages. 3 figures. 2 tables. Accepted for publication in Physical Review C

References in corpus (21)

• Big Bang Nucleosynthesis (in "The Review of Particle Properties" 2004)
• A unitary isobar model for pion photo- and electroproduction on the proton up to 1 GeV
• Dynamical Study of the Delta Excitation in N(e,e' pi) Reactions
• Study of Non-Strange Baryon Resonances with Meson Photoproduction
• Quantization of an interacting spin-3/2 field and the Delta isobar
• Baryon Resonance Extraction from piN Data using a Unitary Multichannel Model
• Field theory of nucleon to higher-spin baryon transitions
• Electromagnetic Properties of the Delta(1232)
• Baryon Octet to Decuplet Electromagnetic Transitions
• The N to Delta electromagnetic transition form factors from Lattice QCD
• Form factors and photoproduction amplitudes
• Quaiselastic scattering from relativistic bound nucleons: Transverse-Longitudinal response
• Multipole Amplitudes of Pion Photoproduction on Nucleons up to 2GeV within Dispersion Relations and Unitary Isobar Model
• Electromagnetic Nucleon-to-Delta Transition in Chiral Effective-Field Theory
• Relativistic mean field approximation to the analysis of 16O(e,e'p)15N data at |Q^2|\leq 0.4 (GeV/c)^2
• Relativistic nuclear structure effects in (e,e' vec{p})
• Deviation of the Nucleon Shape From Spherical Symmetry: Experimental Status
• Pion photoproduction on nucleons in a covariant hadron-exchange model
• Electromagnetic Couplings of Nucleon Resonances
• Unitary ambiguity in the extraction of the E2/M1 ratio for the $\gamma N\leftrightarrow \Delta$ transition
• Effect of form factors in fits to photoproduction data

Cited by in corpus (10)

• Electromagnetic excitation of the Delta(1232)-resonance
• D-state effects in the electromagnetic N-Delta transition
• Effective Lagrangian Approach to pion photoproduction from the nucleon
• Properties of Nucleon Resonances by means of a Genetic Algorithm
• On hadron deformation: a model independent extraction of EMR from pion photoproduction data
• Crossing symmetry and phenomenological widths in effective Lagrangian models of the pion photoproduction process
• Eta Photoproduction as a Test of the Extended Chiral Symmetry
• Analysis of the quadrupole deformation of $\Delta$(1232) within an effective Lagrangian model for pion photoproduction from the nucleon
• Complete Relativistic Description of the N*(1520)
• Spin asymmetry for the 16O(gamma,pi- p) reaction in the Delta(1232) region within an effective Lagrangian approach