Variational method for lattice spectroscopy with ghosts
  We discuss the variational method used in lattice spectroscopy calculations. In particular we address the role of ghost contributions which appear in quenched or partially quenched simulations and have a non-standard euclidean time dependence. We show that the ghosts can be separated from the physical states. Our result is illustrated with numerical data for the scalar meson. 
Tommy Burch, Christof Gattringer, Leonid Ya. Glozman, Christian Hagen,   C.B. Lang