We re-examine the off-shell πN amplitude occurring in the two-pion exchange three-body force, subject to all of the constraints of current algebra. This amplitude is not dominated by the Δ(1231) isobar; instead, if the σ-term is known, it can be determined from on-shell scattering. The resulting contribution to the binding energy of nuclear matter is small but attractive, varying from 0.2 MeV to 1.5 MeV, corresponding to πN σ-terms of 70 MeV to 40 MeV.
ASJC Scopus subject areas
- Nuclear and High Energy Physics