MB amplitudes Jülich DCC

The Jülich-Bonn dynamical coupled-channel analysis of pion- and photon-induced hadronic reactions

Solution JüBo2025:

Coupled-channel contributions to the GDH sum rule from the Jülich-Bonn approach

We study the Gerasimov-Drell-Hearn (GDH) sum rule within a dynamical coupled-channel approach, the Jülich-Bonn model for light baryon resonances based on fits to an extensive data base of pion and photon induced data. Recently published photoproduction data for different observables with πN and ηN final states are analyzed simultaneously with older data for the reactions πN → πN, ηN, KΛ, KΣ and γp → πN, ηN, KΛ, KΣ. The impact of the new data on the resonance spectrum is investigated and the contribution of the individual channels to the GDH integral is determined.

[please refer to arXiv:2508.00598 [nucl-th]]

Comparison of the JüBo2025 solution with photoproduction data and data references:
γp → π0p γp → π+n γp → ηp γp → K⁺Λ γp → K⁺Σ⁰ γp → K⁰Σ⁺
Photoproduction multipoles, comparison with Bonn-Gatchina BG2019 solution:
γp → π0p γp → π+n γp → ηp γp → K⁺Λ γp → K⁺Σ⁰ γp → K⁰Σ⁺
Comparison of the JüBo2025 solution with inelastic piN scattering data and data references:
πN → ηN, KΛ, KΣ
πN → πN partial-wave amplitudes, comparison with GWU-SAID WI08 solution:
πN → πN

Solution JüBo2022:

Light baryon resonances from a coupled-channel study including KΣ photoproduction

The Jülich-Bonn dynamical coupled-channel approach is extended to include KΣ photoproduction off the proton. Differential cross section and (double) polarization data for K⁺Σ⁰ and K⁰Σ⁺ are analysed simultaneously with the pion- and photon-induced production of πN, ηN, KΛ, and KΣ final states, totaling almost 72,000 data points for center-of-mass energies W<2.4 GeV. Based on the fit results the spectrum of N^* and Δ resonances is extracted in terms of pole positions and residues.

[please refer to Eur. Phys. J. A58 (2022) 229 or arXiv:2208.00089 [nucl-th]]

Comparison of the JüBo2022 solution with photoproduction data and data references:
γp → π0p γp → π+n γp → ηp γp → K⁺Λ γp → K⁺Σ⁰ γp → K⁰Σ⁺
Photoproduction multipoles, comparison with Bonn-Gatchina BG2019 solution:
γp → π0p γp → π+n γp → ηp γp → K⁺Λ γp → K⁺Σ⁰ γp → K⁰Σ⁺
Comparison of the JüBo2022 solution with inelastic piN scattering data and data references:
πN → ηN, KΛ, KΣ
πN → πN partial-wave amplitudes, comparison with GWU-SAID WI08 solution:
πN → πN

Solution JüBo_omegaN:

The reaction π N --> ω N in a dynamical coupled-channel approach

A refined investigation on light flavour meson-baryon scattering is performed using a dynamical coupled-channel approach, the Jülich-Bonn model, that respects unitartiy and analyticity constraints. The channel space of πN, πΔ, σN, ρN, ηN, KΛ and KΣ is extended by adding the ωN. The spectra of N^* and Δ resonances are extracted in terms of complex poles of the scattering amplitudes, based on the result of a global fit to a worldwide collection of data, in the energy region from the πN threshold to z=2.3 GeV. A negative value of the ωN elastic scattering length is extracted. This does not support the existence of bound states of the ω meson in nuclear matter.

[please refer to Y.-F. Wang et al., Phys. Rev. D 106 (2022), 094031 or arXiv:2208.03061 [nucl-th]]

Comparison of the JüBo_omegaN solution with inelastic piN scattering data and data references:
πN → ηN, KΛ, KΣ
πN → πN partial-wave amplitudes:
πN → πN

Solution JüBo2017:

The impact of K⁺Λ photoproduction on the resonance spectrum

The Jülich-Bonn coupled-channel framework is extended to K⁺Λ photoproduction. The spectrum of nucleon and Δ resonances is extracted from simultaneous fits to several pion-induced reactions in addition to pion, eta and K⁺Λ photoproduction off the proton. More than 40,000 data points up to a center-of-mass energy of E~2.3 GeV including recently measured double-polarization observables are analyzed.
[please refer to Eur. Phys. J. A 54, 110 (2018) or arXiv:1801.10458]

Comparison of the JüBo2017 solution with photoproduction data and data references:
γp → π0p γp → π+p γp → ηp γp → K⁺Λ
Photoproduction multipoles:
γp → π0p γp → π+p γp → ηp γp → K⁺Λ
Comparison of the JüBo2017 solution with inelastic piN scattering data and data references:
πN → ηN, KΛ, KΣ
πN → πN partial-wave amplitudes:
πN → πN

Solution JüBo2016-1:

Analysis of new polarization data in pion photoproduction

New measurements by the CBELSA/TAPS collaboration of the polarization observables T, E, P, G, and H in γp → π⁰p were included in the coupled-channels JüBo fits.
[please refer to Eur.Phys.J. A52 (2016) 284]

- Comparison of the Jülich2016-1 solution with pion photoproduction data: γp → π0p γp → π+p

- Comparison of the Jülich2016-1 solution with eta photoproduction data: γp → ηp

- Download photoproduction multipoles: γp → π0p γp → π+p γp → ηp

Solution Jülich2015:

Eta photoproduction in a combined analysis of pion- and photon-induced reactions

The resonance spectrum and its properties are determined in a combined analysis of eta and pion photoproduction off the proton
together with the reactions πN → πN, ηN, KΛ and KΣ. [please refer to Eur.Phys.J. A51 (2015) 70]

- Comparison of the Jülich2015 solution with eta photoproduction data: γp → ηp

- Comparison of the Jülich2015 solution with pion photoproduction data: γp → π0p      γp → π+p

- Comparison of the Jülich2015 solution with inelastic piN scattering data: πN → ηN, KΛ, KΣ

- Photoproduction multipoles: γp → π0p      γp → π+p      γp → ηp

                                                     γN → πN (I=1/2)     γN → πN (I=3/2)

- πN → πN partial-wave amplitudes: πN → πN

Solution Jülich2013:

Photocouplings at the pole from pion photoproduction

Photocouplings at the pole are extracted from a combined analysis of the reactions γp → π⁰p and γp → π⁺n. The Jülich2012 dynamical coupled-channel model is employed as the hadronic final-state interaction. [please refer to Eur. Phys. J. A50 (2014) 101]

Comparison of the Jülich2013 solution with pion photoproduction data:

γp → π0p γp → π+p

Solution Jülich2012:

Coupled-channel dynamics in the reactions πN → πN, ηN, KΛ, KΣ

Elastic πN scattering and the reactions π^-p → ηn, K⁰Λ, K⁰Σ⁰, K⁺Σ^- and π⁺p → K⁺Σ⁺ are analyzed simultaneously and the resonance content in terms of pole positions and residues is determined. [please refer to Eur. Phys. J. A49 (2013) 44]

Partial wave amplitudes of the Jülich2012 solution:

For each partial wave L_2I2J the partial wave amplitudes τ for fit A and B are given in the table below, for all on-shell transitions among the channels πN, ηN, KΛ, KΣ.
The ordering of the columns of the individual tables ( L_2I2J.txt files) is defined in this comment .
Further information, such as the definition of τ its relations to observables and the threshold energies can be found here.

S11 A B	P11 A B	S31 A B	P31 A B
P13 A B	D13 A B	P33 A B	D33 A B
D15 A B	F15 A B	D35 A B	F35 A B
F17 A B	G17 A B	F37 A B	G37 A B
G19 A B	H19 A B	G39 A B	H39 A B

All partial waves can be downloaded at once here .

Acknowledgements:

The authors gratefully acknowledge the computing time granted on the supercomputer JURECA at Jülich Supercomputing Centre (JSC).

Impressum Deborah Rönchen, IAS-4, Forschungszentrum Jülich, 52425 Jülich, Germany
Michael Döring, GWU, 725 21st ST NW, Washington DC 20052, USA

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