Improved measurement of $\psi (2S)$ decays into ${\tau }^{+}{\tau }^{-}$

BES Collaboration, M. AblikimJ

Using 14M $\psi (2S)$ events collected at BESII, the branching fraction of $\psi (2S)\to {\tau }^{+}{\tau }^{-}$ is measured to be $B{r}_{\tau \tau }=(3.10\pm 0.21\pm 0.38)\times 10^{-3}$, where the first error…