Baryon masses and pion-nucleon sigma-term to second order in the quark masses

We analyze the octet baryon masses and the pion-nucleon sigma-term in the framework of heavy baryon chiral perturbation theory. In contrast to previous investigations, we include all terms up-to-and-including quadratic order in the light quark masses. The pertinent low-energy constants are fixed from resonance exchange. This leaves as the only free parameter the baryon mass in the chiral limit, (m) over circle. We find (m) over circle=749+/-125 MeV together with sigma(pi N)(0) = 48+/-10 MeV. We discuss various implications of these results.