Weakly coupled Gross-Neveu model with Wilson fermions

The nature of the phase transition in the lattice Gross-Neveu model with Wilson fermions is investigated using a new analytical technique. This involves a new type of weak coupling expansion which focuses on the partition function zeros of the model. Its application to the single flavor Gross-Neveu model yields a phase diagram whose structure is consistent with that predicted from a saddle point approach. The existence of an Aoki phase is confirmed and its width in the weakly coupled region is determined. A parity transformation has the effect of interchanging critical line segments while leaving the full critical curve intact.