Critical exponents of the three-state potts model

The Fernandez-Pacheco duality invariant renormalization group is applied to the hamiltonian version of the two-dimensional three-state Potts model. The fixed point is located at exactly the self-dual critical point K¹ = 1. The thermal exponent is calculated to be y_T=1.1814. This value is in excellent agreement with the low temperature series expansion result of Zwanzig and Ranshaw (y_T = 1.174) and the strong coupling expansion result of Elitzur, Pearson and Shigemitsu (y_T = 1.190). It also seems to lend strong support to den Nijs' recent conjecture that the exact value should be y_T = 6/5.