Measurement of τ decays with the CELLO detector at PETRA

Precise measurements of all major τ branching ratios, determined simultaneously in the same experiment are presented. The results are based on 6064 τ decays observed at √s=35 GeV, using the CELLO detector at PETRA. The sum of the measured branching ratios saturates the total τ decay rate within a statistical error of 2.6 % and a systematic uncertanty of 1.2 %. Comparing with the topological branching ratios measured recently by CELLO, the sums of the respective exclusive branching ratios are found to saturate the inclusive fractions. Our results are in good general agreement with existing measurements. However the decay fractions for τ-→π-π+π-ντ and τ-→π-π0π0ντ are larger than the present world averages. All measured branching ratios are in good agreement with the expectations from a standard τ lepton. (orig.)