VECTOR BREAKING OF REPLICA SYMMETRY IN SOME LOW-TEMPERATURE DISORDERED-SYSTEMS

We present a new method to study disordered systems in the low-tempera ture limit. The method uses the replicated Hamiltonian. It studies the saddle points of this Hamiltonian and shows how the various saddle-po int contributions can be resummed in order to obtain the scaling behav iour at low temperatures. In a large class of strongly disordered syst ems, it is necessary to include saddle points of the Hamiltonian which break the replica symmetry in a vector sector, as opposed to the usua l matrix sector breaking of the spin glass mean-field theory.