Dynamical model for pion-nucleon bremsstrahlung

A dynamical model based on effective Lagrangians is proposed to describe the bremsstrahlung reaction πN⃗πNγ at low energies. The Δ(1232) degrees of freedom are incorporated in a way consistent with both electromagnetic gauge invariance and invariance under contact transformations. The model also includes the initial- and final-state rescattering of hadrons via a T matrix with off-shell effects. The πNγ differential cross sections are calculated using three different T-matrix models and the results are compared with the soft photon approximation, and with experimental data. The aim of this analysis is to test the off-shell behavior of the different T matrices under consideration.