Chiral Perturbation Theory for Staggered Sea Quarks and Ginsparg-Wilson   Valence Quarks
  We study lattice QCD with staggered sea and Ginsparg-Wilson valence quarks. The Symanzik effective action for this mixed lattice theory, including the lattice spacing contributions of O(a^2), is derived. Using this effective theory we construct the leading order chiral Lagrangian. The masses and decay constants of pseudoscalars containing two Ginsparg-Wilson valence quarks are computed at one loop order. 
Oliver Baer, Claude Bernard, Gautam Rupak and Noam Shoresh