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

Using a sample of $448.1×{10}^{6}$ $\psi \left(2S\right)$ events collected with the BESIII detector, we perform a study of the decay $J/\psi \to {K}^{+}{K}^{-}$ via $\psi \left(2S\right)\to {\pi }^{+}{\pi }^{-}J/\psi $. The branching fraction of $J/\psi \to {K}^{+}{K}^{-}$ is determined to be ${B}_{{K}^{+}{K}^{-}}=\left(3.072±0.023\left(\mathrm{stat}\right)±0.050\left(\mathrm{syst}\right)\right)×{10}^{-4}$, which is consistent with previous measurements but with significantly improved precision.