Cosmological Constant, Dark Matter, and Electroweak Phase Transition

TL;DR

This paper investigates how the electroweak phase transition in singlet extensions of the Standard Model could test the fine-tuned cosmological constant hypothesis by examining shifts in dark matter relic abundance.

Contribution

It provides a numerical analysis of relic abundance shifts and identifies parameter space where observable effects are significant in singlet extensions of the Standard Model.

Findings

Identified parameter space with order unity relic abundance shifts

Explicitly computed relic abundance shifts in singlet extensions

Clarified temperature dependence of vacuum energy

Abstract

Accepting the fine tuned cosmological constant hypothesis, we have recently proposed that this hypothesis can be tested if the dark matter freeze out occurs at the electroweak scale and if one were to measure an anomalous shift in the dark matter relic abundance. In this paper, we numerically compute this relic abundance shift in the context of explicit singlet extensions of the Standard Model and explore the properties of the phase transition which would lead to the observationally most favorable scenario. Through the numerical exploration, we explicitly identify a parameter space in a singlet extension of the standard model which gives order unity observable effects. We also clarify the notion of a temperature dependence in the vacuum energy.