Dimensional reduction of the chiral-continuous Gross–Neveu model

We study the finite-temperature phase transition of the generalized Gross–Neveu model with continuous chiral symmetry in 2<d⩽4 euclidean dimensions. The critical exponents are computed to the leading order in the 1/N expansion at both zero and finite temperatures. A dimensionally reduced theory is obtained after the introduction of thermal counterterms necessary to cancel thermal divergences that arise in the limit of high temperature. Although at zero temperature we have an infinitely and continuously degenerate vacuum state, we show that at finite temperature this degeneracy is discrete and, depending on the values of the bare parameters, we may have either total or partial restoration of symmetry. Finally, we determine the universality class of the reduced theory by a simple analysis of the infrared structure of thermodynamic quantities computed using the reduced action as starting point. ©1998 Elsevier Science B.V. All rights reserved.