2004/07/31 by Vladimir Pascalutsa, J. A. Tjon, John A. Tjon
Physics and Astronomy · #Amplitude #Covariant transformation #Degrees of freedom (physics and chemistry) #Hadron #High-Energy Particle Collisions Research #Mathematical physics #Meson #Neutron #Nuclear physics #Nucleon #Omega #Particle physics #Particle physics theoretical and experimental studies #Photodisintegration #Physics #Pion #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #Resonance (particle physics) #Scattering amplitude #hep-ph #nucl-th
paper · pdf · doi:10.1103/physrevc.70.035209
published as Phys.Rev.C70:035209,2004 · 17 pages, 4 figs, version to appear in Phys. Rev. C 70 (2004)
arxiv created 2004/08/30 · openalex publication_date 2004/09/28 · arxiv updated 2014/11/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present a relativistic dynamical model of pion photoproduction on the nucleon in the resonance region. It offers several advances over the existing approaches. The model is obtained by extending our \ensuremathπN-scattering description to the electromagnetic channels. The resulting photopion amplitude is thus unitary in the \ensuremathπN, \ensuremathγN channel space; Watson's theorem is exactly satisfied. At this stage we have included the pion, nucleon, \ensuremathΔ(1232) resonance degrees of freedom. The \ensuremathρ and \ensuremathω meson exchanges are also included, but play a minor role in the considered energy domain (up to √(s)=1.5\phantom\rule0.3em0exGeV). In this energy range the model provides a good description of all the important multipoles. We have allowed for only two free parameters---the photocouplings of the \ensuremathΔ resonance. These couplings are adjusted to reproduce the strength of corresponding resonant-multipoles M1+ and E1+ at the resonance position.