Alpha_s from hadronic tau decay data

TL;DR

This paper presents a refined method for extracting the strong coupling constant alpha_s from tau decay data, achieving results consistent with global electroweak fits by controlling theoretical uncertainties.

Contribution

It introduces an alternative analysis strategy that suppresses poorly known condensate contributions, improving the accuracy of alpha_s extraction from tau decay data.

Findings

Alpha_s(M_Z^2)=0.1187(16) obtained from tau decay data.

Results are in excellent agreement with global electroweak fits.

The method effectively controls theoretical uncertainties related to condensates.

Abstract

We discuss the extraction of alpha_s using isovector hadronic tau decay data and sum rules constructed specifically to suppress contributions associated with poorly known higher dimension condensates. We show, first, that problems with the treatment of such contributions affect earlier related analyses and, second, that these problems can be brought under good theoretical control through the use of an alternate analysis strategy. Our results, run up to the n_f=5 regime, correspond to alpha_s(M_Z^2)=0.1187(16), in excellent agreement with the recently updated global fit to electroweak data at the Z scale and other high-scale direct determinations.