The Baxter model and scale invariant field theory

We investigate the Baxter model and its special case, the two-dimensional Ising model, within the hypothesis of an underlying scale invariant field theory. The translation of the Euclidean lattice expressions for physical operators (spinors, etc.) and pairs of the spin (order), disorder variables of the Ising model to corresponding expressions in terms of relativistic Majorana fields is carried out. All order, disorder correlation functions can be easily computed from the relativistic formulas. The generalization of such correlation functions to the Baxter model is obtained by switching on an energy-energy interaction between two Ising models. The energy-energy coupling turns out to be the Thirring coupling when linear combinations Ψ = Ψ_I + iΨ_II of Majorana fields are introduced. The critical indices α, ν, , γ and β are determined from the correlation functions and are seen to be consistent with the scaling picture.