CRITICAL-BEHAVIOR OF O(N)-SYMMETRICAL SYSTEMS WITH REVERSIBLE MODE-COUPLING TERMS - STABILITY AGAINST DETAILED-BALANCE VIOLATION

We investigate nonequilibrium critical properties of O(n)-symmetric mo dels with reversible mode-coupling terms. Specifically, a variant of t he model of Sasvari, Schwabl, and Szepfalusy (SSS) is studied, where v iolation of detailed balance is incorporated by allowing the order par ameter and the dynamically coupled conserved quantities to be governed by hear baths of different temperatures T-S and T-M, respectively. Dy namic perturbation theory and the field-theoretic renormalization grou p are applied to one-loop order, and yield two new fixed points hi add ition to the equilibrium ones, The first fixed point corresponds to Th eta=T-S/T-M=infinity and leads to model A critical behavior for the or der parameter and to anomalous noise correlations for the generalized angular momenta; the second one is at Theta=0 and is characterized by mean-field behavior of the conserved quantities, by a dynamic exponent Z-d/2 equal io that of the equilibrium SS model, and by modified stat ic critical exponents. However, both these new lived points are unstab le, and upon approaching the critical point detailed balance is restor ed, and the equilibrium static and dynamic critical properties are rec overed.