Coupled Ising fixed points near four dimensions
= Coupled Ising fixed points near four dimensions
The quartic interaction $g_1\phi_1^4+g_2\phi_2^4+\lambda\phi_1^2\phi_2^2$ includes the <Gaussian fixed point>, single and double <Ising model> <Wilson-Fisher fixed points>, and an <O(N) model> fixed point with $N=2$. A rotation of two decoupled identical <Ising models> produces a second coordinate representation of their <renormalization-group fixed point>.