Precision measurement of the branching fraction for the decay $\psi(2S)\rightarrow\tau^{+}\tau^{-}$ at BESIII

Using (2259.3 ± 11.1) × 106𝜓(2𝑆) events acquired with the BESIII detector, the branching fraction of 𝜓(2𝑆) → 𝜏+𝜏− is measured with improved precision to be 𝐵𝑟(𝜓(2𝑆) → 𝜏+𝜏−) = (3.240±0.023±0.081)×10−3,wherethefirstandseconduncertaintiesarestatisticalandsystematic, respectively, which is consistent with the world average value within one standard deviation. This value, along with those for the branching fractions of the 𝜓(2𝑆) decaying into 𝑒+𝑒− and 𝜇+𝜇−, is in good agreement with the relation predicted by the sequential lepton hypothesis.