Sigma-terms in heavy baryon chiral perturbation theory revisited

Abstract

The $σ$-terms are calculated at next-to-leading order in heavy baryon chiral perturbation theory by employing a cutoff regularization. The results do not depend on the cutoff value to the order we are working . The baryon masses and $σ_{πN}(0)$ are used to perform a least-squares fit to the three appearing low-energy constants and predictions for the two $KN$ $σ$-terms and the strange contribution to the nucleon mass are made. The lack of convergence in the chiral expansions of these quantities when regularized dimensionally is overcome in the cutoff scheme. The $σ$-term shifts to the pertinent Cheng-Dashen points are calculated. We also include the spin-3/2 decuplet in the effective theory.