Masses of excited baryons from chirally improved quenched lattice QCD
  Whereas ground state spectroscopy for quenched QCD is well understood, it is still a challenge to obtain results for excited hadron states. In our study we present results from a new approach for determining spatially optimized operators for lattice spectroscopy of excited hadrons. In order to be able to approach physical quark masses we work with the chirally improved Dirac operator, i.e., approximate Ginsparg-Wilson fermions. Since these are computationally expensive we restrict ourselves to a few quark sources. We use Jacobi smeared quark sources with different widths and combine them to construct hadron operators with different spatial wave functions. This allows us to identify the Roper state and other excited baryons, also in the strange sector. 
Tommy Burch, Christof Gattringer, Leonid Ya. Glozman, Christian Hagen,   Dieter Hierl, Reinhard Kleindl, C. B. Lang, and And...