2004/12/13 by R. Alkofer, Reinhard Alkofer, A. Höll +6 · 70 citations
Physics and Astronomy · #Amplitude #Baryon #Combinatorics #Covariant transformation #High-Energy Particle Collisions Research #Mathematical physics #Meson #Momentum (technical analysis) #Momentum transfer #Nucleon #Particle physics #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #Quantum electrodynamics #Quantum mechanics #Quark #Scattering #Vertex (graph theory) #hep-lat #hep-ph #nucl-ex #nucl-th
paper · pdf · doi:10.1007/s00601-005-0110-6
published in Few-Body Systems 37(1-2), 1-31 (Springer Science+Business Media) · 31 pages, 7 figures, 5 tables
arxiv created 2004/12/13 · openalex publication_date 2005/07/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
A Poincare' covariant Faddeev equation, which describes baryons as composites of confined-quarks and -nonpointlike-diquarks, is solved to obtain masses and Faddeev amplitudes for the nucleon and Delta. The amplitudes are a component of a nucleon-photon vertex that automatically fulfills the Ward-Takahashi identity for on-shell nucleons. These elements are sufficient for the calculation of a quark core contribution to the nucleons' electromagnetic form factors. An accurate description of the static properties is not possible with the core alone but the error is uniformly reduced by the incorporation of meson-loop contributions. Such contributions to form factors are noticeable for Q2 < ~2 GeV2 but vanish with increasing momentum transfer. Hence, larger Q2 experiments probe the quark core. The calculated behaviour of GEp(Q2)/GMp(Q2) on Q2 ∈ [2,6] GeV2 agrees with that inferred from polarisation transfer data. Moreover, √(Q2) F2(Q2)/F1(Q2) is approximately constant on this domain. These outcomes result from correlations in the proton's amplitude.