Possible duality violations in tau decay and their impact on the determination of alpha_s

TL;DR

This paper investigates potential duality violations in tau decay data and their effect on the precision of the strong coupling constant alpha_s, suggesting possible systematic errors in its current determination.

Contribution

It introduces a physically motivated ansatz for duality violations and estimates their impact on alpha_s extraction from tau decay data.

Findings

Duality violations may be significant in tau decay.

Current data do not exclude large duality violations.

Systematic errors in alpha_s(m_tau) could be as high as 0.003-0.010.

Abstract

We discuss the issue of duality violations in hadronic tau decay. After introducing a physically motivated ansatz for duality violations, we estimate their possible size by fitting this ansatz to the tau experimental data provided by the ALEPH collaboration. Our conclusion is that these data do not exclude significant duality violations in tau decay. This may imply an additional systematic error in the value of alpha_s(m_tau), extracted from tau decay, as large as \delta alpha_s(m_tau) \sim 0.003-0.010 .