Higgs vacuum (in)stability during inflation: the dangerous relevance of de Sitter departure and Planck-suppressed operators

TL;DR

This paper investigates how small deviations from idealized conditions during inflation, including Planck-scale effects and non-ideal dynamics, critically influence the stability of the Higgs vacuum, linking cosmology with particle physics.

Contribution

It reveals the significant impact of de Sitter departure and Planck-suppressed operators on Higgs stability during inflation, emphasizing the importance of these effects in cosmological models.

Findings

Deviations from exact de Sitter space affect Higgs vacuum stability.

Planck-suppressed operators can destabilize or stabilize the Higgs during inflation.

Non-slow-roll dynamics alter the stochastic behavior of the Higgs field.

Abstract

The measured Standard Model parameters lie in a range such that the Higgs potential, once extrapolated up to high scales, develops a minimum of negative energy density. This has important cosmological implications. In particular, during inflation, quantum fluctuations could have pushed the Higgs field beyond its potential barrier, triggering the formation of anti-de Sitter regions, with fatal consequences for our universe. By requiring that this did not happen, one can in principle connect (and constrain) Standard Model parameters with the energy scale of inflation. In this context, we highlight the sensitivity of the fate of our vacuum to seemingly irrelevant physics. In particular, the departure of inflation from an exact de Sitter phase, as well as Planck-suppressed derivative operators, can, already and surprisingly, play a decisive role in (de)stabilizing the Higgs during inflation. Furthermore, in the stochastic dynamics, we quantify the impact of the amplitude of the noise differing from the one of a massless field, as well as of going beyond the slow-roll approximation by using a phase-space approach. On a general ground, our analysis shows that relating the period of inflation to precision particle physics requires a knowledge of these "irrelevant" effects.