Abstract
The coupled-channels Lagrangian approach underlying the Giessen model (GiM) is extended to describe the scattering in the resonance energy region. As a feasibility study we investigate single- and double-pion production up to the second resonance region. The production has been significantly improved by using the isobar approximation with and in the intermediate state. The three-body unitarity is maintained up to an interference pattern between the isobar subchannels. The scattering amplitudes are obtained as a solution of the Bethe-Salpeter equation in the -matrix approximation. As a first application we perform a partial-wave analysis of the reactions in the Roper resonance region. We obtain and for the and decay branching ratios of , respectively. The extracted inelasticities and reaction amplitudes are consistent with the results from other groups.
16 More- Received 28 September 2014
- Revised 1 December 2015
DOI:https://doi.org/10.1103/PhysRevC.93.045206
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