https://doi.org/10.1140/epja/i2018-12541-3
Regular Article - Theoretical Physics
The impact of 
photoproduction on the resonance spectrum
1
Helmholtz-Institut für Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Universität Bonn, 53115, Bonn, Germany
2
Institute for Nuclear Studies and Department of Physics, The George Washington University, 20052, Washington, DC, USA
3
Thomas Jefferson National Accelerator Facility, 12000 Jefferson Avenue, Newport News, VA, USA
4
Institute for Advanced Simulation, Institut für Kernphysik, Jülich Center for Hadron Physics and JARA HPC, Forschungszentrum Jülich, 52425, Jülich, Germany
* e-mail: roenchen@hiskp.uni-bonn.de
Received:
2
February
2018
Accepted:
20
May
2018
Published online:
26
June
2018
The Jülich-Bonn coupled-channel framework is extended to photoproduction. The spectrum of nucleon and 
resonances is extracted from simultaneous fits to several pion-induced reactions in addition to pion, eta and photoproduction off the proton. More than 40000 data points up to a center-of-mass energy of 
GeV including recently measured double-polarization observables are analyzed. The influence of the 
channel on the extracted resonance parameters and the appearance of states not seen in other channels is investigated. The Jülich-Bonn model includes effective three-body channels and guarantees unitarity and analyticity, which is a prerequisite for a reliable determination of the resonance spectrum in terms of poles and residues.
© SIF, Springer-Verlag GmbH Germany, part of Springer Nature, 2018
