Pion photoproduction on nucleons in a covariant hadron-exchange model

Journal Article · Wed Sep 01 04:00:00 EDT 2004 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PhysRevC.70.035209· OSTI ID:20695547

Pascalutsa, Vladimir ^[1]; Tjon, John A ^[1]

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1. Theory Group, Jefferson Laboratory, 12000 Jefferson Avenue, Newport News, Virginia 23606 (United States)

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 {pi}N-scattering description to the electromagnetic channels. The resulting photopion amplitude is thus unitary in the {pi}N, {gamma}N channel space; Watson's theorem is exactly satisfied. At this stage we have included the pion, nucleon, {delta}(1232) resonance degrees of freedom. The {rho} and {omega} meson exchanges are also included, but play a minor role in the considered energy domain (up to {radical}(s)=1.5 GeV). 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 {delta} resonance. These couplings are adjusted to reproduce the strength of corresponding resonant-multipoles M{sub 1+} and E{sub 1+} at the resonance position.

• OSTI ID: 20695547
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 3 Vol. 70; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BOSON-EXCHANGE MODELS
DEGREES OF FREEDOM
DELTA-1232 BARYONS
ENERGY-LEVEL TRANSITIONS
GEV RANGE
MULTIPOLES
NUCLEAR FORCES
OMEGA-782 MESONS
PHOTON-NUCLEON INTERACTIONS
PHOTOPRODUCTION
PION-NUCLEON INTERACTIONS
PIONS
RELATIVISTIC RANGE
RHO-770 MESONS
SCATTERING AMPLITUDES