Inverse symmetry breaking on the lattice: an accurate MC study

We present here a new MC study of ISB at finite temperature in a Z(2) X Z(2 ) lambda phi(4) model in four dimensions. The results of our simulations, e ven if not conclusive, are favourable to ISB. Detection of the effect requi red measuring some critical couplings with six-digit precision, a level of accuracy that could be achieved only by a careful use of FSS techniques. Th e gap equations for the Debye masses, resulting from the resummation of the ring diagrams, seem to provide a qualitatively correct description of the data, while the simple one-loop formulae appear to be inadequate. (C) 1999 Published by Elsevier Science B.V. All rights reserved.