αs(MZ²) from hadronic τ decays

Abstract

We perform an extraction of αs based on sum rules involving isovector hadronic τ decay data. The particular sum rules employed are constructed specifically to suppress contributions associated with poorly known higher dimension condensates, and hence reduce theoretical systematic uncertainties associated with the treatment of such contributions which are shown to be present in earlier related analyses. Running our results from the nf=3 to nf=5 regime we find αs(MZ2)=0.1187±0.0016, in excellent agreement with the recently updated global fit to electroweak data at the Z scale and other high-scale direct determinations.