  The extraction of meson-baryon scattering parameters from lattice QCD is
complicated by the necessity, in some channels, of including annihilation
diagrams. We consider a strategy to avoid the need for these extremely costly
and noisy contributions. The strategy is based on simulations with an isospin
chemical potential which, contrary to a baryon chemical potential, has no sign
problem. When the isospin chemical potential is larger than a critical value, a
charged pion condensate forms. Baryons propagating in the pion condensate will
have their masses modified by pion-baryon scattering parameters. Consequently
these parameters can be extracted from lattice QCD simulations in an isospin
chemical potential, and we detail precisely which low-energy constants using
baryon chiral perturbation theory.
