$\alpha_{s}$ from the (revised) ALEPH data for $\tau$ decay

TL;DR

This paper provides a new analysis of the strong coupling constant alpha_s from revised ALEPH tau decay data, comparing different perturbation theories and combining results with previous OPAL data for the most reliable estimate.

Contribution

It introduces a novel analysis strategy for alpha_s extraction from tau decay data and compares it with traditional methods, improving the reliability of the results.

Findings

Alpha_s(m_tau^2) = 0.296 ± 0.010 (fixed-order)

Alpha_s(m_tau^2) = 0.310 ± 0.014 (contour-improved)

Combined alpha_s(m_tau^2) ≈ 0.303–0.319 with reduced uncertainty

Abstract

We present a new analysis of $\alpha_s$ from hadronic $\tau$ decays based on the recently revised ALEPH data. The analysis is based on a strategy which we previously applied to the OPAL data. We critically compare our strategy to the one traditionally used and comment on the main differences. Our analysis yields the values $\alpha_s(m_\tau^2)=0.296\pm 0.010$ using fixed-order perturbation theory, and $\alpha_s(m_\tau^2)=0.310\pm 0.014$ using contour-improved perturbation theory. Averaging these values with our previously obtained values from the OPAL data, we find $\alpha_s(m_\tau^2)=0.303\pm 0.009$, respectively, $\alpha_s(m_\tau^2)=0.319\pm 0.012$, as the most reliable results for $\alpha_s$ from $\tau$ decays currently available.