Parameterization dependence ofT-matrix poles and eigenphases from a fit toπNelastic scattering data

Abstract

We compare fits to πN elastic scattering data, based on a Chew-Mandelstam K-matrix formalism. Resonances, characterized by T -matrix poles, are compared in fits generated with and without explicit Chew-Mandelstam K-matrix poles. Diagonalization of the S matrix yields the eigenphase representation. While the eigenphases can vary significantly for the different parameterizations, the locations of most T -matrix poles are relatively stable.

Eta photoproduction in a combined analysis of pion- and photon-induced reactions

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Improved empirical parametrizations of theγ*N→Δ(1232)andγ*N<

“…However, in the present case, the inclusion of the constraints at the pseudo-threshold [25,35,36] and Refs. [37,38] …”

“…Since the average presented by the PDG is affected by a large errorbar, which will leave the region near Q 2 = 0 weakly constrained, we take into account only the most recent measurements selected by PDG, presented in Refs. [37,38].…”

Matching Pion-Nucleon Roy-Steiner Equations to Chiral Perturbation Theory

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