Excited hadrons from improved interpolating fields
  The calculation of quark propagators for Ginsparg-Wilson-type Dirac operators is costly and thus limited to a few different sources. We present a new approach for determining spatially optimized operators for lattice spectroscopy of excited hadrons. Jacobi smeared quark sources with different widths are combined to construct hadron operators with different spatial wave functions. We study the Roper state and excited rho and pion mesons. 
Tommy Burch, Christof Gattringer, Leonid Ya. Glozman, Reinhard   Kleindl, C. B. Lang, and Andreas Sch\"afer