Perturbative Quark Mass Corrections to the Tau Hadronic Width

The perturbative quark-mass corrections to the $\tau$ hadronic width are analysed to $O({\alpha }_s^3{m}_q^2)$, using the presently available theoretical information. The behaviour of the perturbative series is investigated in order to assess the associated uncertainties. The implications for the determination of the strange quark mass from $\tau$ decay data are discussed.