A precision measurement of the tau lifetime

The authors present a high statistics measurement of the τ lepton lifetime. The data used in this analysis were collected with the CLEO detector at CESR and consist of an integrated luminosity of 429 pb-1 taken at energies on, above, and below the Λ(4S). The selected sample consists of τ+τ- pairs, produced in e+e- annihilations, in which one τ decays only to leptons and the other decays to three charged particles. The authors reconstruct 4206 three charged track decay vertices and use a weighted average of the vertex displacements to determine the τ lifetime. They measure the τ lifetime to be (3.04 ± 0.14 ± 0.07) x 10-13 sec