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arXiv · 1112.5025

Remarks on the complex branch points in pi-N scattering amplitude and the multiple poles structure of resonances

Shin Nan Yang
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Abstract

A simple heuristic argument to understand the existence of branch points in the unphysical sheet for pi-N scattering amplitude is presented. It is based on a hypothesis that the singularity structure of the pi-N scattering amplitude is a smooth varying function of the pion mass. We find that, in general, multiple poles structure of a resonance is a direct mathematical consequence when additional Riemann surface is included in the study and the two-pole structure found to correspond to the Roper resonance is a good example.

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Shin Nan Yang. 2011-12-21. Remarks on the complex branch points in pi-N scattering amplitude and the multiple poles structure of resonances. https://arxiv.org/abs/1112.5025

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