Universal effective action for the three-dimensional ising ferromagnet

Abstract

We compute the universal effective action for one-component real scalar field in three Euclidean dimensions, in the case of spontaneously broken symmetry, from the Monte Carlo simulation of the three-dimensional Ising model. We find that, in close analogy with the symmetric case, the effective potential is very well approximated by the sum of φ 2 , φ 4 and φ 6 terms. An unexpected feature is the negative sign of the φ 4 term.