Two-dimensional Ising and Potts model with long-range bond disorder: A renormalization group approach

Abstract

In this paper we provide new analytic results on two-dimensional q-Potts models (q ≥ 2) in the presence of bond disorder correlations which decay algebraically with distance with exponent a. In particular, our results are valid for the long-range bond disordered Ising model (q = 2). We implement a renormalization group perturbative approach based on conformal perturbation theory. We extend to the long-range case the RG scheme used in [V. Dotsenko et al., Nucl. Phys. B 455 701-23] for the short-range disorder. Our approach is based on a 2-loop order double expansion in the positive parameters (2 − a) and (q − 2). We will show that the Weinrib-Halperin conjecture for the long-range thermal exponent can be violated for a non-Gaussian disorder. We compute the central charges of the long-range fixed points finding a very good agreement with numerical measurements.