PERTURBATIVE QCD AND TAU-DECAY

Sufficiently inclusive observables in the decay of the tau lepton can be calculated using the methods of perturbative QCD. These include the asymmetry parameter A(tau) that determines that angular distribution of the total hadron momentum in the decay of a polarized tau. It shoul d be possible to measure A(tau) accurately using existing data from LE P. Reliable estimates of theoretical errors are essential in order to determine whether a given observable is sufficiently inclusive to be c alculated using perturbative methods. The theoretical uncertainties du e to higher orders in alpha(s) can be estimated using recent calculati ons to all orders in the large-(33-2N(f)) limit. These estimates indic ate that tau decay data can be used to determine alpha(s)(M-Z) to a pr ecision of 2% or better.