Including the $\Delta (1232)$ resonance in baryon chiral perturbation theory

Abstract

Baryon chiral perturbation theory with explicit $\Delta (1232)$ degrees of freedom is considered. Using the extended on-mass-shell renormalization scheme, a manifestly Lorentz-invariant effective field theory with a systematic power counting is obtained. As applications we discuss the mass of the nucleon, the pion-nucleon sigma term, and the pole of the $\Delta$ propagator.

Comments: 18 pages, 2 figures, REVTeX 4