Axionic Landscape for Higgs Near-Criticality

TL;DR

This paper proposes that an axionic landscape can explain the Higgs near-criticality by creating a multiverse with varying quartic couplings, making our universe's parameters statistically likely to be near the stability boundary.

Contribution

It introduces a model where an axionic field generates a landscape of Higgs quartic couplings, providing a possible anthropic explanation for the Higgs near-criticality.

Findings

Probability distribution peaks near the stability boundary.

Multiverse scenarios depend on different Higgs vacuum selection mechanisms.

Most probable universe is close to the critical boundary, consistent with observations.

Abstract

The measured value of the Higgs quartic coupling $\lambda$ is peculiarly close to the critical value above which the Higgs potential becomes unstable, when extrapolated to high scales by renormalization group running. It is tempting to speculate that there is an anthropic reason behind this near-criticality. We show how an axionic field can provide a landscape of vacuum states in which $\lambda$ scans. These states are populated during inflation to create a multiverse with different quartic couplings, with a probability distribution $P$ that can be computed. If $P$ is peaked in the anthropically forbidden region of Higgs instability, then the most probable universe compatible with observers would be close to the boundary, as observed. We discuss three scenarios depending on the Higgs vacuum selection mechanism: decay by quantum tunneling; by thermal fluctuations or by inflationary fluctuations.