SPIN-SPIN CRITICAL-POINT CORRELATION-FUNCTIONS FOR THE 2D RANDOM BONDISING AND POTTS MODELS

We compute the combined two and three loop order correction to the spi n-spin correlation functions for the 2D Ising and q-states Potts model with random bonds at the critical point. The procedure employed is th e renormalisation group approach for the perturbation series around th e conformal field theories representing the pure models. We obtain cor rections for the correlations functions which produce crossover in the amplitude but don't change the critical exponent in the case of the I sing model and which produce a shift in the critical exponent, due to randomness, in the case of the Potts model. Comparison with numerical data is discussed briefly.