Constraints on variation in $\alpha$ and $m_e$ from WMAP 7-year data

TL;DR

This paper uses the latest WMAP 7-year data and other cosmological observations to place constraints on possible variations of the fine structure constant and electron mass over cosmic time, refining previous bounds.

Contribution

It provides updated bounds on the variation of fundamental constants using a modified cosmological analysis with new data sets and explores their joint and individual variations.

Findings

Constraints on $eta_ ext{EM}$ and $eta_ ext{F}$ parameters are tighter with latest data.

Allowed variation in $eta_ ext{F}$ is within 1% at 1-$\sigma$ level.

Variation in $m_e$ is constrained to within a few percent.

Abstract

We update the constraints on the time variation of the fine structure constant $\alpha$ and the electron mass $m_e$, using the latest CMB data, including the 7-yr release of WMAP. We made statistical analyses of the variation of each one of the constants and of their joint variation, together with the basic set of cosmological parameters. We used a modified version of CAMB and COSMOMC to account for these possible variations. We present bounds on the variation of the constants for different data sets, and show how results depend on them. When using the latest CMB data plus the power spectrum from Sloan Digital Sky Survey LRG, we find that $\alpha / \alpha_0=0.986 \pm 0.007$ at 1-$\sigma$ level, when the 6 basic cosmological parameters were fitted, and only variation in $\alpha$ was allowed. The constraints in the case of variation in both constants are $ \alpha / \alpha_0= 0.986 \pm 0.009$ and $m_e / m_{e0} = 0.999 \pm 0.035$. In the case of only variation in $m_e$, the bound is $m_e /m_{e0}=0.964 \pm 0.025$.