Correlated correlation functions in random-bond ferromagnets

The two-dimensional random-bond e-state Ports model is studied for Q near 2 via the perturbative renormalisation group to one loop. It is shown that w eak disorder induces cross-correlations between the quenched-averages of mo ments of the two-point spin/spin and energy/energy correlation functions, w hich should be observable numerically in specific linear combinations of va rious quenched correlation functions. The random-bond Ising model in (2 + e psilon) dimensions is similarly treated. As a byproduct, a simple method fo r deriving the scaling dimensions of all moments of the local energy operat or is presented. (C) 2000 Elsevier Science B.V. All rights reserved.