Universality of coupled Potts models Original Research Article

We study systems of M Potts models coupled by their local energy density. Each model is taken to have a distinct number of states, and the permutational symmetry SM present in the case of identical coupled models is thus broken initially. The duality transformations within the space of 2M−1 multi-energy couplings are shown to have a particularly simple form. The selfdual manifold has dimension DM=2M−1−1. Specialising to the case M=3, we identify a unique non-trivial critical point in the three-dimensional selfdual space. We compare its critical exponents as computed from the perturbative renormalisation group with numerical transfer matrix results. Our main objective is to provide evidence that at the critical point of three different coupled models the symmetry S3 is restored.