Metastable Electroweak Vacuum: Implications for Inflation

TL;DR

This paper explores how a small positive coupling between the Higgs and inflaton fields can resolve the cosmological issues posed by the metastability of the electroweak vacuum during inflation.

Contribution

It introduces a mechanism involving Higgs-inflaton coupling to explain vacuum stability and initial conditions in the early universe.

Findings

Higgs-inflaton coupling can stabilize the electroweak vacuum during inflation.

Fine-tuning of initial Higgs conditions can be alleviated by this coupling.

The proposed model addresses cosmological vacuum stability issues.

Abstract

Within the Standard Model, the current Higgs and top quark data favor metastability of the electroweak vacuum, although the uncertainties are still significant. The true vacuum is many orders of magnitude deeper than ours and the barrier separating the two is tiny compared to the depth of the well. This raises a cosmological question: how did the Higgs field get trapped in the shallow minimum and why did it stay there during inflation? The Higgs initial conditions before inflation must be fine--tuned to about one part in 10^8 in order for the Higgs field to end up in the right vacuum. In this note, we show that these problems can be resolved if there is a small positive coupling between the Higgs and the inflaton.