Lattice QCD with a twisted mass term and a strange quark
  There are three quarks with masses at or below the characteristic scale of QCD dynamics: up, down and strange. However, twisted mass lattice QCD relies on quark doublets. Various options for including three quark flavors within the twisted mass approach are explored by studying the kaon masses, both analytically (through chiral Lagrangians) and numerically (through lattice simulations). Advantages and disadvantages are revealed for each ``strange and twisted'' option. 
Abdou M. Abdel-Rehim, Randy Lewis, R. M. Woloshyn and Jackson M. S. Wu