The nucleon sigma term from threshold parameters

A new sum rule determines the nucleon sigma term by the πN elastic scattering threshold parameters alone. This “threshold” value of σ(2μ2) provides an independent check of existing values obtained from global dispersive analyses, and also provides a realistic error assignment. Employing a recent analysis of low energy (Tπ<100 MeV) πN data our sum rule implies σ(2μ2)=71±9 MeV.