Meson Systems with Ginsparg-Wilson Valence Quarks
  Unphysical effects associated with finite lattice spacing and partial quenching generally lead to to the presence of unphysical terms in chiral extrapolation formulae, which must be removed to make physical predictions. We use mixed action effective field theory to discuss that through next-to-leading order, simulations of meson systems which employ valence quarks satisfying the Ginsparg-Wilson relation (lattice-chiral symmetry), depend only upon the physical counterterms of interest, provided one uses a lattice-physical (on-shell) renormalization scheme. With this lattice-physical renormalization, the I = 2 pi-pi, I = 3/2 K-pi, I=1 K-K meson scattering lengths combined with f_K / f_pi share only two linearly independent counterterms, both of which are physical. This allows us to make use of existing lattice QCD simulations to make a prediction of the I = 1 K-K scattering length. 
A. Walker-Loud