# Observational Constraints on Varying Alpha in $\Lambda(\alpha)$CDM Cosmology

## TL;DR

This paper investigates a cosmological model where the cosmological constant varies with the fine-structure constant, constrained by observations, and explores how a scalar field coupling affects this variation.

## Contribution

It provides observational constraints on a $
m \Lambda(
m \alpha)$CDM model with a varying fine-structure constant and scalar field coupling to electromagnetism.

## Key findings

- Constraints on the variation of alpha from observational data.
- Impact of scalar field coupling on the evolution of alpha.
- Limits on the model parameters from cosmological observations.

## Abstract

In this work, we consider the so-called $\Lambda(\alpha)$CDM cosmology with $\Lambda\propto\alpha^{-6}$ while the fine-structure "constant" $\alpha$ is varying. In this scenario, the accelerated expansion of the universe is driven by the cosmological "constant" $\Lambda$ (equivalently the vacuum energy), and the varying $\alpha$ is driven by a subdominant scalar field $\phi$ coupling with the electromagnetic field. The observational constraints on the varying $\alpha$ and $\Lambda\propto\alpha^{-6}$ models with various couplings $B_F(\phi)$ between the subdominant scalar field $\phi$ and the electromagnetic field are considered.