- The paper demonstrates that quantum fluctuations during inflation can push the Higgs field over its potential barrier into unstable regimes.
- It employs stochastic methods and thermal corrections during reheating to derive constraints on the Hubble rate and electroweak metastability.
- It explores the relativistic dynamics of Higgs bubbles and suggests links between vacuum instability and quantum gravitational effects.
An Examination of Cosmological Vacuum Instability due to the Higgs
The paper entitled "The Cosmological Higgstory of the Vacuum Instability" discusses the implications of potential vacuum instability in the Standard Model (SM) due to fluctuations in the Higgs field. The authors examine how these fluctuations interact with cosmological evolution, especially during inflation and reheating periods, and derive constraints on physical parameters like the Hubble constant during inflation based on the preservation of a metastable electroweak vacuum.
The analysis begins by considering the stability of the Higgs potential. The mass measurements of the Higgs boson and the top quark imply that, without any additional new physics beyond the SM, the vacuum is near a critical boundary; it's teetering between stability and instability. The focus is on the potential's instability at very large field values, well below the Planck scale. In this context, cosmologically forming patches or "bubbles" of space where the Higgs field explores these dangerous regions pose risks of transitioning into lower-energy states, which could be catastrophic on a universal scale.
During inflation, quantum fluctuations could push the Higgs field over the potential barrier towards this unstable region, raising significant cosmological concerns. The paper explores the role of the Hubble rate, as larger inflationary Hubble rates increase dangerous fluctuations. The authors derive formulas that describe the evolution of the Higgs field with a stochastic process and confirm that fluctuations can result in Higgs field values within the boundary of vacuum instability.
The authors perform a sophisticated analysis of post-inflation physics, taking into account the processes of reheating and thermal bath influences. These are significant because thermal corrections applied to the Higgs potential during the reheating process may stabilize fluctuations, rescuing regions of space where these surpass the potential barrier from evolving to the anti-de Sitter minimum.
The work also rigorously explores the general relativistic dynamics of these Higgs bubbles—regions of space wherein the Higgs field density surpasses stability thresholds. A domain wall separates these bubbles and is explored by the relativistic junction conditions and ADM mass interpretations, allowing insight into the possible evolution either in remaining in de Sitter or transitioning to AdS space or expanding indefinitely.
Moreover, the paper touches on intriguing and speculative interpretations linking cosmological vacuum stability with quantum gravitational theories. Reasoning through the lens of quantum gravity, it hints at a predictive framework for Higgs and top quark masses and presents arguments against stable de Sitter spaces due to theoretical consistencies, potentially punctuated by the Higgs vacuum instability as a cosmological "exit strategy".
These conclusions have profound implications for early universe cosmology, providing constraints on inflationary models and insisting on the necessity of checking for AdS bubbles in our light-cone history, lest they imply a future instability. Future observational strides, particularly in determining aspects like the Hubble rate in inflationary epochs, may be crucial to test these theoretical assertions on Higgs vacuum dynamics and cosmological inflationary histories. This work thus contributes essential constraints and explores fascinating interrelations between particle physics, cosmology, and quantum gravity.