Discussion on upper limit of the precision for tau mass measurement

摘要

tau lepton is one of three charged leptons in nature, the measurements of its mass have been performed since its discovery. The present relative accuracy is already at the level of 10(-4); more factors are still being studied in order to increase the accuracy. However, the available techniques for analysis and expectable luminosity from e(+) e(-) collider indicate that the precision upper limit of tau mass is almost reached, which means that brand new approaches should be considered if a great improvement is yearned for.