The three-dimensional Thirring model for Nf=4 and Nf=6

We present Monte Carlo simulation results for the three-dimensional Thirring model for numbers of fermion flavours N-f = 4 and 6. For N-f = 4 we find a second-order chiral symmetry breaking transition at strong coupling, corresponding to an ultra-violet fixed point of the renormalisation group defining a non-trivial continuum limit. The critical exponents extracted from a fit to a model equation of state are distinct from those found for N-f = 2. For N-f = 6, in contrast, we present evidence for tunnelling between chirally symmetric and broken vacua at strong coupling, implying that the phase transition is first-order and no continuum limit exists. The implications for the phase diagram of the model in the plane of coupling strength and Nr are briefly discussed. (C) 1999 Elsevier Science B.V. All rights reserved.