Looking for a varying α in the cosmic microwave background

We perform a likelihood analysis of the recently released BOOMERanG and MAXIMA data, allowing for the possibility of a time-varying fine-structure constant. We find that in general these data prefer a value of α that was smaller in the past (which is in agreement with measurements of α from quasar observations). However, there are some interesting degeneracies in the problem which imply that strong statements about α cannot be made using this method until independent accurate determinations of ${\Omega }_b{h}^2$ and $H_0$ are available. We also show that a preferred lower value of $\alpha$ comes mainly from the data points around the first Doppler peak, whereas the main effect of the high-$l$ data points is to increase the preferred value for ${\Omega }_b{h}^2$ (while also tightening the constraints on ${\Omega }_0$ and $H_0).\mathrm{}$ We comment on some implications of our results.