Precision measurement of the branching fraction of \boldmath $J/ψ\rightarrow K^+K^-$ via $ψ(2S)\rightarrow π^+π^-J/ψ$

Abstract

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

to be submitted to PRD