Spectral functions from hadronic τ dacays

Abstract

Hadronic decays of the τ lepton provide a clean environment to study hadron dynamics in an energy regime dominated by romances, with the interesting information captured in the spectral functions. Recent results on exclusive channels are reviewed. Inclusive spectral functions are the basis for QCD analyses, delivering an accurate determination of the strong coupling constant and quantitative information on nonpertubative contributions. the τ vector spectral functions for the 2π and 4π final states are used together with e p+ e p- data in order to compute vacuum polarization integrals occuring in the calculations of the anomalous magnetic moment of the moun and the running of the electromagnetic coupling.