CLASSICAL BEHAVIOR IN QUANTUM-MECHANICS - A TRANSITION-PROBABILITY APPROACH

A formalism is developed for describing approximate classical behavior in finite (but possibly large) quantum systems. This is done in terms of a structure common to classical and quantum mechanics, viz. a Pois son space with a transition probability. Both the limit where HBAR --> 0 in a fixed finite system and the limit where the size of the system goes to infinity are incorporated. In either case, classical behavior is seen only for certain observables and in a restricted class of sta tes.