Pole positions and residues from pion photoproduction using the Laurent+Pietarinen expansion method

Abstract

We have applied a new approach to determine the pole positions and residues from pion photoproduction multipoles. The method is based on a Laurent expansion of the partial wave T-matrices, with a Pietarinen series representing the regular part of energy-dependent and single-energy photoproduction solutions. The method has been applied to multipole fits generated by the MAID and GWU/SAID groups. We show that the number and properties of poles extracted from photoproduction data correspond very well to results from $\pi$N elastic data and values cited by Particle Data Group (PDG). The photoproduction residues provide new information for the electromagnetic current at the pole position, which are independent of background parameterizations, as opposed to the Breit-Wigner representation. Finally, we present the photo-decay amplitudes from the current MAID and SAID solutions at the pole, for all four-star nucleon resonances below W=2 GeV.

23 pages, 5 figures, 9 tables. arXiv admin note: text overlap with arXiv:1401.1947

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Cited by in corpus (8)

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• Light Baryon Spectroscopy
• Strange resonance poles from $K\pi$ scattering below 1.8 GeV
• Strong evidence for nucleon resonances near 1900\,MeV
• Differential Cross Section Measurements for $\gamma n\to {\pi }^{-}p$ Above the First Nucleon Resonance Region
• Pole structure from energy-dependent and single-energy fits to $\pi N$ elastic scattering data
• $N^{\ast }$ resonances from $K\Lambda$ amplitudes in sliced bins in energy