Higgs portal valleys, stability and inflation

Understand

The measured values of the Higgs and top quark masses imply that the Standard Model potential is very likely to be unstable at large Higgs values.

• This is particularly problematic during inflation, which sources large perturbations of the Higgs.
• The instability could be cured by a threshold effect induced by a scalar with a large vacuum expectation value and directly connected to the Standard Model through a Higgs portal coupling.
• However, we find that in a minimal model in which the scalar generates inflation, this mechanism does not stabilize the potential because the mass required for inflation is beyond the instability scale.