Review of τ lifetime measurements

Abstract

The measurements of the mean lifetime of the τ lepton are reviewed. The conditions for measuring the lifetime at various e + e − colliders are compared and the analysis methods are briefly described. The new developments since the previous Workshop on Tau Lepton Physics are listed. The world average is τ τ = 290.5 ± 1.0 fs. The LEP experiments dominate this average and have analyzed nearly all of their data. In anticipation of the next era of precision measurements at CLEO and the b factories, the important sources of systematic errors and the treatment of systematic biases are discussed.