Generalized Ward-Takahashi identities and current algebras

Abstract

Generalized Ward-Takahashi identities are written for current algebras generated by conserved and partially conserved currents. The application to meson-baryon scattering is discussed and expressions for the scattering lengths are derived. An approximation is obtained for the real part of the low-energy forward meson-nucleon scattering amplitude; this gives sum rules for the low-energy phase shifts. Some questions arising from off-mass-shell extrapolations are discussed.