Radiative Symmetry Breaking from Flat Potential in various U(1)' models
  We investigate a radiative electroweak gauge symmetry breaking scenario via the Coleman-Weinberg mechanism starting from a completely flat Higgs potential at the Planck scale ("flatland scenario"). In our previous paper, we showed that the flatland scenario is possible only when an inequality K<1 among the coefficients of the beta functions is satisfied. In this paper, we calculate the number K in various models with an extra U(1) gauge sector in addition to the SM particles. We also show the renormalization group (RG) behaviors of a couple of the models as examples. 
Michio Hashimoto, Satoshi Iso, Yuta Orikasa
hep-ph hep-th