Tau-decay determination of the strong coupling

TL;DR

This paper reviews and consolidates various methods for determining the strong coupling constant from tau decay data, resulting in a precise and reliable value consistent across approaches.

Contribution

It provides a comprehensive analysis of tau decay data using multiple strategies, achieving a robust determination of the strong coupling constant with well-assessed uncertainties.

Findings

Consistent results across different methodologies.

Precise value of alpha_s at tau mass scale: 0.328±0.013.

Derived alpha_s at Z boson mass: 0.1197±0.0015.

Abstract

We review the current status of the determination of the strong coupling from tau decay. Using the most recent release of the ALEPH data, a very comprehensive phenomenological analysis has been performed, exploring all strategies previously considered in the literature and several complementary approaches. Once their actual uncertainties are properly assessed, the results from all adopted methodologies are in excellent agreement, leading to a very robust and reliable value of the strong coupling, $\alpha_s^{(n_f=3)}(m_\tau^2) = 0.328\pm 0.013$, which implies $\alpha_s^{(n_f=5)}(M_Z^2) = 0.1197\pm 0.0015$.