Do we understand the role of incoherent interactions in many-body physics?

Recent developments in many-body quantum chaos show that a quantum system w ith strong incoherent interactions can still he described with the aid of m ean quasiparticle occupation numbers as in Fermi liquid theory. Wt: use the se ideas and the geometric chaoticity of angular momentum coupling to expla in the predominance of ground states with zero spin and the maximum possibl e spin for a system of randomly interacting fermions in a rotationally inva riant mean field tan analog of the Hund rule). We show that spin ordering c oexists with the chaotic features of the ground-state wave functions. (C) 2 001 MAIK "Nauka/Interperiodica".