Critical analysis of baryon masses and sigma-terms in heavy baryon chiral perturbation theory

We present an analysis of the octet baryon masses and the πN and KN σ-terms in the framework of heavy baryon chiral perturbation theory. At next-to-leading order, O(q³), knowledge of the baryon masses and σ_πN(0) allows to determine the three corresponding finite low-energy constants and to predict the two KN σ-terms σ_KN^(1,2)(0). We also include the spin-3/2 decuplet in the effective theory. The presence of the non-vanishing energy scale due to the octet-decuplet splitting shifts the average octet baryon mass by an infinite amount and leads to infinite renormalizations of the low-energy constants. The first observable effect of the decuplet intermediate states to the baryon masses starts out at order q⁴. We argue that it is not sufficient to retain only these but no other higher order terms to achieve a consistent description of the three-flavor scalar sector of baryon CHPT. In addition, we critically discuss an SU (2) result which allows to explain the large shift σ_πN(2 M_π²)-σ_πN(0) via intermediate Δ (1232) states.