Pion photoproduction in a dynamical coupled-channel model

Pion photoproduction reactions are investigated in a dynamical coupled‐channel approach based on the Jülich πN model, which presently includes the hadronic πN and ηN stable channels as well as the πΔ, σN and ρN effective channels. This model has been quite successful in the description of $\mathrm{\pi N\to \pi N}$ scattering for center‐of‐mass energies up to 1.9 GeV. The full pion photoproduction amplitude is constructed to satisfy the generalized Ward‐Takahashi identity and hence, it is fully gauge invariant. The calculated differential cross sections and photon spin asymmetries up to 1.65 GeV center‐of‐mass energy for the reactions ${\mathrm{\gamma p\to \pi }}^{+}\mathrm{n,}$ ${\mathrm{\gamma p\to \pi }}^{0}p$ and ${\mathrm{\gamma n\to \pi }}^{-}p$ are in good agreement with the experimental data.