Extracting the σ-term from low-energy pion-nucleon scattering

@article{Elvira2017ExtractingT,
  title={Extracting the $\sigma$-term from low-energy pion-nucleon scattering},
  author={Jacobo Ruiz de Elvira and Martin Hoferichter and Bastian Kubis and Ulf-G. Mei{\ss}ner},
  journal={Journal of Physics G},
  year={2017},
  volume={45},
  pages={024001}
}
We present an extraction of the pion-nucleon (πN) scattering lengths from low-energy πN scattering, by fitting a representation based on Roy–Steiner equations to the low-energy data base. We show that the resulting values confirm the scattering-length determination from pionic atoms, and discuss the stability of the fit results regarding electromagnetic corrections and experimental normalization uncertainties in detail. Our results provide further evidence for a large πN σ-term, σπN = 58(5) MeV… 

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