Measurement of the tau lepton mass by the Beijing Spectrometer (BES) Collaboration.

摘要

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.