Extracting $\sigma_{\pi N}$ from pionic atoms
Abstract
We discuss a recent extraction of the term from a large-scale fit of pionic-atom strong-interaction data across the periodic table. The value thus derived, MeV, is directly connected via the Gell-Mann--Oakes--Renner expression to the medium-renormalized isovector scattering amplitude near threshold. It compares well with the value derived recently by the Bern-Bonn-J\"{u}lich group, MeV, using the Roy-Steiner equations to control the extrapolation of the vanishingly small near threshold isoscalar scattering amplitude to zero pion mass.
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