Excited-State Hadron Masses from Lattice QCD
  Progress in computing the spectrum of excited baryons and mesons in lattice QCD is described. Large sets of spatially-extended hadron operators are used. The need for multi-hadron operators in addition to single-hadron operators is emphasized, necessitating the use of a new stochastic method of treating the low-lying modes of quark propagation which exploits Laplacian Heaviside quark-field smearing. A new glueball operator is tested, and computing the mixing of this glueball operator with a quark-antiquark operator and multiple two-pion operators is shown to be feasible. 
Colin Morningstar, John Bulava, Justin Foley, You-Cyuan Jhang, Keisuke   Juge, David Lenkner, Chik Him Wong
hep-lat nucl-th