Boundary Criticality of the 3D O(N) Model: From Normal to Extraordinary.

Abstract

It was recently realized that the three-dimensional O(N) model possesses an extraordinary boundary universality class for a finite range of N≥2. For a given N, the existence and universal properties of this class are predicted to be controlled by certain amplitudes of the normal universality class, where one applies an explicit symmetry breaking field to the boundary. In this Letter, we study the normal universality class for N=2, 3 using MonteCarlo simulations on an improved lattice model and extract these universal amplitudes. Our results are in good agreement with direct MonteCarlo studies of the extraordinary universality class serving as a nontrivial quantitative check of the connection between the normal and extraordinary classes.