On shell, subtracted dispersion relations and low energy theorems from current algebra

Abstract

A method discussed in an earlier paper is applied to the case of ππ and πN scattering and to electroproduction. As an example we derive for the ππ scattering amplitude a subtracted, covariant on-shell dispersion relation in which the subtraction polynomial is determined by the corresponding low energy theorem plus possibly small corrections. We also show how this same method may be applied to the derivation of low energy theorems.