Higgs mass implications on the stability of the electroweak vacuum

TL;DR

This paper updates the bounds on the stability of the electroweak vacuum considering recent Higgs measurements, showing that the vacuum could be metastable with a lifetime longer than the universe, and discusses implications for early universe conditions.

Contribution

It provides updated stability bounds of the Standard Model vacuum incorporating recent experimental data and explores implications for inflation and neutrino mass models.

Findings

Higgs mass 124-126 GeV allows metastability with a very long lifetime.

Stability up to the Planck scale cannot be excluded due to errors.

Reheat temperature bounds depend on Higgs and top masses, affecting baryogenesis scenarios.

Abstract

We update instability and metastability bounds of the Standard Model electroweak vacuum in view of the recent ATLAS and CMS Higgs results. For a Higgs mass in the range 124--126 GeV, and for the current central values of the top mass and strong coupling constant, the Higgs potential develops an instability around $10^{11}$ GeV, with a lifetime much longer than the age of the Universe. However, taking into account theoretical and experimental errors, stability up to the Planck scale cannot be excluded. Stability at finite temperature implies an upper bound on the reheat temperature after inflation, which depends critically on the precise values of the Higgs and top masses. A Higgs mass in the range 124--126 GeV is compatible with very high values of the reheating temperature, without conflict with mechanisms of baryogenesis such as leptogenesis. We derive an upper bound on the mass of heavy right-handed neutrinos by requiring that their Yukawa couplings do not destabilize the Higgs potential.