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arXiv · hep-ph/9408312

Compton Scattering by a Pion and off--Shell Effects

S. Scherer·H. W. Fearing
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Abstract

We consider Compton scattering by a pion in the framework of chiral perturbation theory. We investigate off--shell effects in the s-- and u--channel pole diagrams. For that purpose we perform a field transformation which, in comparison with the standard Gasser and Leutwyler Lagrangian, generates additional terms at order $p^4$ proportional to the lowest--order equation of motion. As a result of the equivalence theorem the two Lagrangians predict the same Compton scattering S--matrix even though they generate different off--shell form factors. We conclude that off--shell effects are not only model--dependent but also representation--dependent.

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S. Scherer, H. W. Fearing. 1994-08-17. Compton Scattering by a Pion and off--Shell Effects. https://doi.org/10.1103/physrevc.51.359

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