  We use two-flavor chiral perturbation theory to describe hyperons. We focus
on the strangeness conserving sector, and, as an example, calculate hyperon
masses. Convergence of this two-flavor chiral expansion for observables is
improved over the three-flavor theory. The cost, however, is a larger number of
low-energy constants that must be ultimately determined from lattice QCD data.
A formula for the mass of the omega baryon is derived to sixth order in this
expansion, and will aid lattice practitioners in scale setting or tuning the
strange quark mass.
