On the cosmological implications of the electroweak vacuum instability: constraining the non-minimal coupling with inflation

TL;DR

This paper explores how the metastability of the electroweak vacuum during inflation can constrain the Higgs non-minimal coupling to gravity, providing new bounds based on inflationary models and the Higgs potential.

Contribution

It introduces a method to constrain the Higgs curvature coupling using vacuum metastability during inflation, considering dynamic Hubble rates and various inflationary scenarios.

Findings

Derived lower bounds on the Higgs-curvature coupling $\xi$ for different inflation models

Showed the impact of the Hubble rate evolution on the Higgs potential stability

Provided constraints consistent with current cosmological observations

Abstract

Our current measurements of the Standard Model parameters imply that the Higgs field resides in a metastable electroweak vacuum, where the vacuum can decay to a lower ground state, with cataclysmic repercussions for our Universe. According to our observations, no such event has happened in the observable universe, in spite of the various energetic processes that could have triggered it. This work serves as an overview of a method that uses the metastability of the false vacuum during cosmological inflation to provide constraints on the Higgs curvature coupling $\xi$. Considering also the effects of the time-dependent Hubble rate on the effective Higgs potential and on our past light-cone space-time geometry, results in state-of-the-art lower $\xi$-bounds from quadratic and quartic chaotic inflation, and Starobinsky-like power-law inflation.