Stabilization of the Electroweak Vacuum by a Scalar Threshold Effect
  We show how a heavy scalar singlet with a large vacuum expectation value can evade the potential instability of the Standard Model electroweak vacuum. The quartic interaction between the heavy scalar singlet and the Higgs doublet leads to a positive tree-level threshold correction for the Higgs quartic coupling, which is very effective in stabilizing the potential. We provide examples, such as the see-saw, invisible axion and unitarized Higgs inflation, where the proposed mechanism is automatically implemented in well-defined ranges of Higgs masses. 
Joan Elias-Mir\'o, Jos\'e R. Espinosa, Gian F. Giudice, Hyun Min Lee,   Alessandro Strumia
hep-ph hep-th