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 that was smaller in the past (which is in agreement with measurements of from quasar observations). However, there are some interesting degeneracies in the problem which imply that strong statements about cannot be made using this method until independent accurate determinations of ₁h^2 and H₀ are available. We also show that a preferred lower value of 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 ₁h^2 (while also tightening the constraints on ₀ and H₀). We comment on some implications of our results.