Thermal Phase Transition in the NJL Model of QCD

We present results from numerical studies of the NJL model with two massless quarks at nonzero temperature. We show that the model undergoes a second order chiral phase transition which belongs to the 3d O(4) spin model universality class.Comment: 4 pages, Presented at "Phase Transitions in Strongly Interacting Matter", Prague, 23 - 29 August 200

Non-compact QED(3) coupled to a four-fermi interaction

We present preliminary numerical results for the three dimensional non-compact QED with a weak four-fermion term in the lattice action. Approaches based on Schwinger-Dyson studies, arguments based on thermodynamic inequalities and numerical simulations lead to estimates of the critical number of fermion flavors (below which chiral symmetry is broken) ranging from $N_{fc}=1$ to $N_{fc}=4$. The weak four-fermion coupling provides the framework for an improved algorithm, which allows us to simulate the chiral limit of massless fermions and expose delicate effects.Comment: 3 pages, Contribution to Lattice2004(chiral), Fermilab, June 21-26, 200

The (2+1)-dimensional Gross-Neveu model with a U(1) chiral symmetry at non-zero temperature

We present results from numerical simulations of the (2+1)-dimensional Gross-Neveu model with a U(1) chiral symmetry and N_f=4 fermion species at non-zero temperature. We provide evidence that there are two different chirally symmetric phases, one critical and one with finite correlation length, separated by a Berezinskii-Kosterlitz-Thouless transition. We have also identified a regime above the critical temperature in which the fermions acquire a screening mass even in the absence of chiral symmetry breaking, analogous to the pseudogap behaviour observed in cuprate superconductors.Comment: 12 pages, 6 figure