INSTABILITY OF THE RANDOM FIXED-POINT OF RENORMALIZATION-GROUP FOR THE SPIN SYSTEMS WITH QUENCHED DISORDER

The replica trick used in the renormalization group (RG) for the disor dered spin systems is discussed, The recursion relations of RG are der ived in a more general situation in which the coupling constants can h ave arbitrary symmetry to the replica indices. If is shown that the ra ndom fixed point found by Luther, Grinstein and Lubensky is unstable, This instability implies that the replica symmetry should be broken in the RG for the disordered systems.