Measurement of the Mass of the τ Lepton

Abstract

A data-driven energy ecan in the immediate vicinity of the 7 pair production tbreshold has been performed using the Beijing Spectrometer at the Beijing Electron-Positron Collider. Approximately 5 pb-' of data, distributed over 12 ecan points, have been collected. A previous maee value for the 7 lepton, obtained using only the ep final state, has been published. In this paper, the final BES result on the maes measurement is presented. The analysis is based on the combined data from the ee, ep, eh, VW, ph, and hh final states, where h denotes a charged ?(or K. A maximum likelihood fit to the r pair production cross section data yields the value rn, = 1776.96+~:~~!~:~~ MeV.