BAI, JZ (reprint author), INST HIGH ENERGY PHYS,BEIJING 100039,PEOPLES R CHINA.
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+ e- --> tau+ tau- was performed. Candidate events were identified by requiring that one tau decay via tau --> enunuBAR, and the other via tau --> mununuBAR. The mass value, obtained from a fit to the energy dependence of the tau+ tau- cross section, is m(tau) = 1776.9(-0.5)+0.4 +/- 0.2 MeV.