Non-trivial critical exponents for finite temperature chiral transitions at fixed total fermion number

We analyze the finite temperature chiral restoration transition of the (D = d + 1)-dimensional Gross-Neveu model for the case of a large number of fla vors and fixed total fermion number. This leads to the study of the model w ith a nonzero imaginary chemical potential. In this formulation of the theo ry, we have obtained that, in the transition region, the model is described by a chiral conformal field theory where the concepts of dimensional reduc tion and universality do apply due to a transmutation of statistics which m akes fermions act as if they were bosons, having zero energy. This result s hould be generic for theories with dynamical symmetry breaking, such as Qua ntum Chromodynamics. (C) 1998 Elsevier Science B.V. All rights reserved.