Environment Dependent Electron Mass and the H$_0$-Tension

TL;DR

This paper proposes a mechanism involving a density-dependent scalar field to explain a potential difference in electron mass between recombination and today, aiming to address the Hubble tension.

Contribution

It introduces a symmetron scalar field coupled via Yukawa interaction to account for environment-dependent electron mass variations.

Findings

A density-dependent scalar field can modify electron mass over cosmic time.

The model provides a potential solution to the Hubble tension.

Possible observable effects of the scalar field are discussed.

Abstract

A difference in the electron mass at recombination from the measured value today has been shown to relieve the Hubble tension. In this article we propose a simple mechanism that would allow for such a mass difference. Similar in form to the Higgs field, we consider a Yukawa coupling between the symmetron scalar field and the electron. However, the symmetron vacuum expectation value depends on the matter density of its environment which, in principle, would allow its contribution towards the electron mass to differ between recombination and today. We detail the coupling and discuss possible observables.