The informational-statistical-entropy operator in a nonequilibrium ensemble formalism

We study the eigenvalue spectrum of the informational-statistical-entropy o perator, a quantity that plays a fundamental role in the nonequilibrium sta tistical operator method. We obtain explicit expressions for the informatio nal entropy for inhomogeneous nonequilibrium (dissipative) systems, relevan t for the study of its nonclassical nonlinear hydrodynamics. Expressions fo r the single-particle dynamical matrix and, in particular, for the distribu tion functions of quasi-particles, in conditions arbitrarily away from equi librium, are also derived. We apply the results considering some aspects of the hydrodynamics of a Fermion system in weak interaction with a thermal b ath of Bosons. (C) 1999 Elsevier Science B.V. All rights reserved.