Remarks on the pion-nucleon σ-term

The pion-nucleon sigma-term can be stringently constrained by the combination of analyticity, unitarity, and crossing symmetry with phenomenological information on the pion-nucleon scattering lengths. Recently, lattice calculations at the physical point have been reported that find lower values by about 3 sigma with respect to the phenomenological determination. We point out that a lattice measurement of the pion-nucleon scattering lengths could help resolve the situation by testing the values extracted from spectroscopy measurements in pionic atoms. (C) 2016 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license.