Susceptibility of the checkerboard Ising model

The authors show that at the disorder variety, the n-point correlation functions of the checkerboard Potts model have a simple causal structure, and decay as simple exponentials for space-like separations. An exact expression for the susceptibility in the Ising case is obtained. The result is additional evidence in favour of the conjectured S<SUB>4</SUB> symmetry of the checkerboard Potts model in the presence of a finite field