Pion photoproduction through the Δ resonance region: relativistic versus non-relativistic unitary models

M. Vanderhaeghen, K. Heyde, J. Ryckebusch, M. Waroquier
Nuclear Physics A
595 (2), 219-258
Published while none of the authors were employed at the CMM


A fully relativistic, gauge invariant and unitary pion photoproduction model is constructed including π, ϱ, ω, N and Δ degrees of freedom. The model is compared in detail to pion photoproduction observables in view of several sets of high-quality data that were obtained through the Δ resonance region in recent years. Starting from the relativistic model, a non-relativistic model mean ffor calculations in the nuclear medium is derived. The non-relativistic model is constructed to satisfy unitarity and is applied to both charged and neutral pion photoproduction with the same parameter set.