English

Extracting $\sigma_{\pi N}$ from pionic atoms

Nuclear Theory 2020-08-11 v2 High Energy Physics - Phenomenology

Abstract

We discuss a recent extraction of the πN\pi N σ\sigma term σπN\sigma_{\pi N} from a large-scale fit of pionic-atom strong-interaction data across the periodic table. The value thus derived, σπNFG=57±7\sigma_{\pi N}^{\rm FG}=57\pm 7 MeV, is directly connected via the Gell-Mann--Oakes--Renner expression to the medium-renormalized πN\pi N isovector scattering amplitude near threshold. It compares well with the value derived recently by the Bern-Bonn-J\"{u}lich group, σπNRS=58±5\sigma_{\pi N}^{\rm RS}=58\pm 5 MeV, using the Roy-Steiner equations to control the extrapolation of the vanishingly small near threshold πN\pi N isoscalar scattering amplitude to zero pion mass.

Keywords

Cite

@article{arxiv.2008.03147,
  title  = {Extracting $\sigma_{\pi N}$ from pionic atoms},
  author = {Eliahu Friedman and Avraham Gal},
  journal= {arXiv preprint arXiv:2008.03147},
  year   = {2020}
}

Comments

10 pages, 3 figures; presented at the 15th International Conference on Meson-Nucleon (MENU) Physics and the Structure of the Nucleon, Pittsburgh, and in a slightly different form at the 3rd Jagiellonian Symposium on Fundamental and Applied Subatomic Physics, Krak\'ow, both in June 2019; v2: typos corrected

R2 v1 2026-06-23T17:42:18.887Z