A Study of Symmetry Restoration at Finite Temperature in the O(4) Model   Using Anisotropic Lattices
  Results of investigations of the O(4) spin model at finite temperature using anisotropic lattices are presented. In both the large $N$ approximation and the numerical simulations using the Wolff cluster algorithm we find that the ratio of the symmetry restoration temperature $T_{\rm SR}$ to the Higgs mass $m_{\rm H}$ is independent of the anisotropy. We obtain a lower bound of $0.59 \pm 0.04$ for the ratio, $T_{\rm SR}/m_{\rm H}$, at $m_{\rm H}a \simeq 0.5$, which is lowered further by about 10% at $m_{\rm H}a \simeq 1.$ 
R.V. Gavai, U.M. Heller, F. Karsch, B. Plache, and T. Neuhaus