τ Decays: the solution to a longstanding problem

Precise measurements of the exclusive decay channels of the τ lepton, using the CELLO detector at PETRA, are presented. The data are from a high statistics run at 35 GeV. The sum of these branching ratios saturates to 100% within better than 2%. Most of the exclusive branching ratios are in agreement with existing measurements. However, the decays τ- → e- antiνν τ, τ- → π- π+ π- ντ and τ- → π- π0 π0ντ are somewhat larger than the present world averages. Comparing with the precise topological branching ratios measured recently by CELLO, consistency is found with the sum of the respective exclusive branching ratios. All measured branching ratios are in good agreement with the expectations from a standard τ lepton