Thermodynamics of Lattice QCD with massless quarks and chiral 4-fermion   interactions
  We have simulated lattice QCD with an irrelevant 4-fermion interaction and 2 zero mass quarks. The chiral phase transition is observed to be second order and we discuss extraction of critical exponents. 
J. B. Kogut, J.-F. Lagae and D. K. Sinclair