Electroweak vacuum lifetime in two Higgs doublet models

TL;DR

This paper analyzes the stability and lifetime of electroweak vacua in two Higgs doublet models, highlighting how vacuum degeneracy influences tunneling times and constrains model parameters based on cosmological considerations.

Contribution

It provides a detailed calculation of vacuum lifetimes in two Higgs doublet models considering degeneracy effects, linking theoretical stability to experimental constraints.

Findings

Degenerate vacua significantly affect lifetime calculations.

Certain parameter regions are excluded due to rapid tunneling.

Model viability is constrained by vacuum stability considerations.

Abstract

We study the stability of neutral electroweak vacua in two Higgs doublet models, and calculate the lifetime of these states when the parameters are such that they are false vacua. As the two Higgs doublet model is invariant under a sign change of both doublets, degenerate true vacua exist. It is shown that this degeneracy, despite the fact that each of these minima locally describes the same physics, can immensely affect their lifetime. We apply these calculations to the parameter space of the models which is allowed by recent LHC searches, and infer combinations of parameters which should be excluded on grounds of a tunneling time inferior to the age of the universe.