alpha_s at low Q^2 from e+e- and tau data

TL;DR

This paper compares e+e- and tau decay data to test QCD predictions at low Q^2, evaluating spectral moments to assess the potential for precision tests with current and future experiments.

Contribution

It introduces a method to use e+e- data for QCD tests similar to tau decay analyses and predicts achievable accuracy with upcoming experimental data.

Findings

e+e- spectral moments can be used for QCD tests

Comparison with tau data shows consistency within uncertainties

Projected data precision could improve QCD validation

Abstract

It has been shown in recent analyses by ALEPH [1] and OPAL [2] that precision QCD tests are possible with hadronic tau decays by comparing spectral moments of the hadronic decay ratio of the tau with QCD calculations. In principle e+e- data can be used in a similar manner by evaluating spectral moments of R. The current e+e- data is compared with the OPAL tau data and a prediction is made on the achievable accuracy of QCD tests with the projected precision of PEP-N [3].