Toward Group Theory Operators for tmLQCD Hadrons
  Extraction of the mass spectrum from twisted mass lattice QCD is facilitated by respecting the octahedral group of rotations and accommodating the broken parity and flavor symmetries of the theory. In this work, group theory meson operators adapted to these constraints are constructed for the special case of quark and antiquark fields at a common lattice site, connected by extended gauge field paths. 
Derek Harnett, Randy Lewis and Robert G. Petry