Download or read book Measurement of the Tau Lepton Mass by the Beijing Spectrometer (BES) Collaboration written by and published by . This book was released on 1992 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: The mass of the [tau] lepton has been measured at the Beijing Electron Positron Collider using the Beijing Spectrometer. A search near threshold for e[sup +]e[sup [minus]] [yields] [tau][sup +][tau][sup [minus]] was performed. Candidate events were identified by requiring that one [tau] decay via [tau] [yields] e[nu][bar [nu]], and the other via [tau] [yields] [mu][nu][bar [nu]]. The mass value, obtained from a fit to the energy dependence of the [tau][sup +][tau][sup [minus]] cross section, is m[sub [tau]] = 1776.9[sub -0.5][sup +0.4] [plus minus] 0.2 MeV.