Critical Flavor Number in the Three Dimensional Thirring Model

Abstract

We present results of a Monte Carlo simulation of the three dimensional Thirring model with the number of fermion flavors N_f varied between 2 and 18. By identifying the lattice coupling at which the chiral condensate peaks, simulations are be performed at couplings g^2(N_f) corresponding to the strong coupling limit of the continuum theory. The chiral symmetry restoring phase transition is studied as N_f is increased, and the critical number of flavors estimated as N_{fc}=6.6(1). The critical exponents measured at the transition do not agree with self-consistent solutions of the Schwinger-Dyson equations; in particular there is no evidence for the transition being of infinite order. Implications for the critical flavor number in QED_3 are briefly discussed.