Vacuum selection by inflation as the origin of the dark energy

TL;DR

The paper proposes a cosmological mechanism where inflation selects a vacuum state in a non-Abelian Higgs theory, naturally explaining the tiny but finite dark energy observed today without fine-tuning.

Contribution

It introduces a novel inflation-based vacuum selection process in non-Abelian Higgs theories to account for dark energy, avoiding the need for tiny parameters.

Findings

Dark energy magnitude is exponentially suppressed by instanton action.

Inflation homogenizes field configurations, leading to a superposition of vacua.

The model fits observed dark energy without fine-tuning.

Abstract

I propose a new mechanism to account for the observed tiny but finite dark energy in terms of a non-Abelian Higgs theory, which has infinitely many perturbative vacua characterized by a winding number, in the framework of inflationary cosmology. Inflation homogenizes field configuration and practically realizes a perturbative vacuum with vanishing winding number, which is expressed by a superposition of eigenstates of the Hamiltonian with different vacuum energy density. As a result, we naturally find a nonvanishing vacuum energy density with fairly large probability, under the assumption that the cosmological constant vanishes in some vacuum state. Since the predicted magnitude of dark energy is exponentially suppressed by the instanton action, we can fit observation without introducing any tiny parameters.