Excited-State Hadron Masses from Lattice QCD

Understand

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.