By using the new result of τ-mass from Beijing spectrometer and the data ofτ→5πv_(τ)from ARGUS,the upper limit of v_(τ)-mass of 30 MeV is obtained at 95%confidence level.The upper limit of the v_(τ)-mass could be largely reduced if a high resolution detector is used in the improved Beijing electron positron collider,which is under discussion.
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