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A gauge invariant unitary theory for pion photoproduction

C. H. M. van Antwerpen·I. R. Afnan
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Abstract

The Ward-Takahashi identities are central to the gauge invariance of the photoproduction amplitude. Here we demonstrate that unitarity and in particular the inclusion of both the $πN$ and $γπN$ thresholds on equal footing yields a photoproduction amplitude that satisfies both two-body unitarity and the generalized Ward-Takahashi identities. The final amplitude is a solution of a set of coupled channel integral equations for the reactions $πN\rightarrowπN$ and $γN\rightarrowπN$. % Figures available from the authors upon request, % e-mail: phchv@pippin.cc.flinders.edu.au % Submitted to Physical Review C

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C. H. M. van Antwerpen, I. R. Afnan. 1994-07-25. A gauge invariant unitary theory for pion photoproduction. https://doi.org/10.1103/physrevc.52.554

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