Electroweak Instantons, Axions, and the Cosmological Constant

TL;DR

This paper explores how electroweak instantons and axions could explain the observed dark energy, linking high-energy physics phenomena to cosmological constant observations.

Contribution

It proposes a novel connection between electroweak instantons, axions, and the cosmological constant without requiring new physics between the electroweak and Planck scales.

Findings

Electroweak instantons induce a { heta}-dependence sensitive to high energy scales.

An electroweak axion can produce a vacuum energy difference matching dark energy.

The model does not require new physics between electroweak and Planck scales.

Abstract

If there is explicit violation of baryon plus lepton number at some energy scale, then the electroweak theory depends upon a {\theta}-angle. Due to a singular integration over small scale size instantons, this {\theta}-dependence is sensitive to very high momentum scales. Assuming that there is no new physics between the electroweak and Planck scales, for an electroweak axion the energy difference between the vacuum at {\theta} /= 0, and that at {\theta} = 0, is of the correct order of magnitude to be the dark energy observed in the present epoch.