The 15th International Workshop on Tau Lepton Physics (TAU2018)
Ontological classification
Academic field:
Physics
Specialties:
High-Energy Physics - Phenomenology
Approach:
Theoretical
Abstract
We discuss sum-rule determinations of $\alpha_s$ {from} non-strange hadronic {$\tau$-decay} data. We investigate, in particular, the reliability of {the} assumptions {underlying the ``truncated OPE strategy,'' which specifies a certain treatment of non-perturbative contributions, and which was employed in Refs.~\cite{Pich,Aleph, Opal}. Here, we test this strategy by applying the strategy to the $R$-ratio obtained from $e^+e^-$ data, which extend beyond the $\tau$ mass, and{, based on the outcome of these tests, we} demonstrate the failure of this strategy.} {We then present a brief overview of} new results on the form of {duality-violating non-perturbative} contributions, which are conspicuously present in the experimentally determined spectral functions. As we show, with the current precision claimed for the extraction of $\alpha_s$, including a representation of {duality violations} is unavoidable if one wishes to avoid uncontrolled theoretical errors.
