Precision measurement of the branching fraction of \boldmath $J/\psi \to K^{+}{K}^{-}$ via $\psi (2S)\to {\pi }^{+}{\pi }^{-}J/\psi$

BESIII Collaboration, M. Ablikim, M. N. Achasov +615

Using a sample of $448.1\times 10^6$ $\psi (2S)$ events collected with the BESIII detector, we perform a study of the decay $J/\psi \to K^{+}{K}^{-}$ via $\psi (2S)\to {\pi }^{+}{\pi }^{-}J/\psi$. T…