Spectral functions from Hadronic Tau Decays and QCD

TL;DR

This paper reviews how hadronic tau decays and spectral functions are used to study QCD phenomena, including resonance dynamics, strong coupling, and quark masses, with recent ALEPH results highlighting their importance.

Contribution

It provides an overview of recent experimental results on spectral functions from tau decays and their application in QCD analyses, emphasizing the role of the $ au$ decay data in understanding strong interactions.

Findings

Accurate determination of the strong coupling constant from spectral functions.

Quantitative insights into nonperturbative QCD contributions.

Measurement of the strange quark mass using tau decay data.

Abstract

Hadronic decays of the $\tau$ lepton provide a clean environment to study hadron dynamics in an energy regime dominated by resonances, with the interesting information captured in the spectral functions. Recent results from ALEPH on exclusive channels are presented, with some emphasis on the $\pi \piz$ final state which plays a crucial role for the determination of the hadronic contribution to the muon anomalous magnetic moment. Inclusive spectral functions are the basis for QCD analyses, delivering an accurate determination of the strong coupling constant, quantitative information on nonperturbative contributions and a measurement of the mass of the strange quark.