Hadronic tau decays and the strong coupling

TL;DR

This paper reviews methods for determining the strong coupling constant from hadronic tau decays, comparing two approaches and emphasizing the reliability of the DV-model approach over the truncated-OPE method, with prospects for improved precision using new data.

Contribution

It critically assesses two analysis methods for extracting alpha_s from tau decays, advocating for the DV-model approach based on ALEPH data and discussing future improvements with Belle data.

Findings

The truncated-OPE approach is quantitatively unreliable.

The DV-model approach passes all consistency tests.

New Belle and Belle-II data could refine alpha_s measurements.

Abstract

We provide an overview of recent determinations of the strong coupling, $\alpha_s$, from hadronic $\tau$ decays. We contrast two analysis methods, the "truncated-OPE approach" and the "DV-model approach," highlighting the assumptions going into each of these. We argue that a detailed study based on ALEPH data shows the truncated-OPE approach to be quantitatively unreliable, while the DV-model approach passes all tests. New data for hadronic $\tau$ decays from Belle and Belle-II could provide more stringent tests of the DV-model approach, and thus potentially lead to a more precise value of $\alpha_s$ from hadronic $\tau$ decays.